![This research design is to determine the relationship between one thing
[an independent variable] and another [a dependent or outcome
variable] within a population.
It is either descriptive [subjects usually measured once] or experimental
[subjects measured before and after a treatment].
It also deals in numbers, logic, and an objective stance. Quantitative
research focuses on numeric and unchanging data and detailed,
convergent reasoning rather than divergent reasoning [i.e., the
generation of a variety of ideas about a research problem in a
spontaneous, free-flowing manner].](https://image.slidesharecdn.com/pptonvariables-250115092144-c2aadf6e/85/PowerPoint-presentation-on-Variables-in-research-81-320.jpg)
PowerPoint presentation on Variables in research
- 2. The Scientific Method Scientific method It is a process that is used to find answers to questions about the world around us.
- 3. Scientific method There are several versions of the scientific method. Some versions have more steps, while others may have only a few. However, they all begin with the identification of a problem or a question to be answered based on observations of the world around us.
- 4. VARIABLES It is defined as an attribute of an object of study. Data is a specific measurement of a variable and it is the value you record in your data sheet. In research, variables are any characteristics that can take on different values. In scientific research, we often want to study the effect of one variable on another one. For example, you might want to test whether students who spend more time studying get better exam scores.
- 5. VARIABLES It may be weight, height, anxiety levels, income, body temperature and so on. Each of these properties varies from one person to another and also has different values along a continuum. It could be demographic, physical or social and include religion, income, occupation, temperature, humidity, language, food, fashion, etc. Some variables can be quite concrete and clear, such as gender, birth order, types of blood group etc while others can be considerably more abstract and vague
- 6. TYPES OF VARIABLES There are different types of variables: • Independent • Dependent • Active and attribute • Continuous • Discrete and categorical • Extraneous variables and Demographic variables
- 7. Dependent and Independent Variables Dependent Variable(s): The response or factors that are measured during a study. The dependent variable responds to the independent variable. Independent variables are what we expect will influence dependent variables. A Dependent variable is what happens as a result of the independent variable. For example, if we want to explore whether high concentrations of vehicle exhaust impact incidence of asthma in children, vehicle exhaust is the independent variable while asthma is the dependent variable.
- 8. A discrete variable is a variable whose value is obtained by counting. Examples: number of students present number of children with malaria • A continuous variable is a variable whose value is obtained by measuring. Examples: height of students in class weight of students in class time it takes to get to school
- 9. ACTIVE AND ATTRIBUTE VARIABLES An active variable is a variable that can be manipulated. Active variables are also called experimental variables. Examples of this type of variable are teaching methods, training regimens, and the like, which can be altered to gauge their effect on phenomena. An attribute variable is a variable that cannot be manipulated. An example of an attribute variable is gender, race, psychological condition, and or any characteristic that is inherent or pre-programmed and cannot be altered.
- 10. EXTRANEOUS VARIABLES Variables that may affect research outcomes but have not been adequately considered in the study are termed as extraneous variables. Extraneous variables exist in all studies and can affect the measurement of study variables and the relationship among these variables. Extraneous variables that are not recognized until the study is in process, or are recognized before the study is initiated but cannot be controlled, are referred to as confounding variables”
- 11. • Certain external variables may influence the relationship between the research variables, even though researcher cannot see it. • These variables are called intervening variables. For example, girl’s knowledge and practices helps in maintaining menstrual hygiene. • Here, motivation, mother and friends, mass media, are some intervening variables which may also help in maintaining menstrual hygiene. • Thus, if these two factors are not controlled it would be impossible to know what the underlying cause really is.
- 12. Discrete variable Discrete variables are numeric variables that have a countable number of values between any two values. A discrete variable is always numeric. Discrete data is information that can only take certain values. These values don’t have to be whole numbers for example amount of sugar in the blood, height of students in a class
- 13. Categorial variables A categorical variable is a discrete variable that captures qualitative outcomes by placing observations into fixed groups (or levels). The groups are mutually exclusive, which means that each individual fits into only one category. The variable gender, for example, has only two values (male and female). Variables that take on only a handful of discrete non quantitative values are categorical variables.
- 14. DEMOGRAPHIC VARIABLES Demographic variables are characteristics or attributes of subjects that are collected to describe the sample”. They are also called sample characteristics. It means these variables describe study sample and determine if samples are representative of the population of interest. Although demographic variables cannot be manipulated, Researchers can explain relationships between demographic variables and dependent variables. Some common demographic variables are age, gender, occupation, marital status, income etc.
- 15. MEASURING VARIABLES In order to do an analysis, the variables have to be quantified; this means measuring giving values and scale. Sometimes identification of variables and determining how to measure them looks quite simple, but due to vaguely defined variables measuring can be difficult too. There are four levels of measurements on a continuum of discrete and continuous: nominal-scale, ordinal-scale, interval-scale and ratio-scale. Nominal scale is used when the variables can be categorized but cannot be ranked. E.g. gender, marital status, race, diagnosis, blood group etc.
- 16. Ordinal scale includes statistical data type where variables are in order or rank but without a degree of difference between categories. The ordinal scale contains qualitative data; ‘ordinal’ meaning ‘order’. It places variables in order/rank, only permitting to measure the value as higher or lower in scale. The scale cannot generate a precise comparison between the two categories. Interval scale can be defined as a quantitative measurement scale where variables have an order, the difference between two variables is equal, and the presence of zero is arbitrary. It can be used to measure variables that exist along a common scale in equal intervals. A ratio scale is a quantitative scale where there is a true zero and equal intervals between neighboring points. Unlike on an interval scale, a zero on a ratio scale means there is a total absence of the variable you are measuring. Length, area, and population are examples of ratio scales
- 17. CLINICAL STUDY A clinical study involves research using human volunteers (also called participants) that is intended to add to medical knowledge. There are two main types of clinical studies: clinical trials (also called interventional studies) and observational studies (Non Intervention Studies).
- 18. Clinical Trials In a clinical trial, participants receive specific interventions according to the research plan or protocol created by the investigators. These interventions may be medical products, such as drugs or devices; procedures; or changes to participants' behavior, such as diet. Clinical trials may compare a new medical approach to a standard one that is already available, to a placebo that contains no active ingredients, or to no intervention.
- 19. When a new product or approach is being studied, it is not usually known whether it will be helpful, harmful, or no different than available alternatives (including no intervention). The investigators try to determine the safety and efficacy of the intervention by measuring certain outcomes in the participants. For example, investigators may give a drug or treatment to participants who have high blood pressure to see whether their blood pressure decreases.
- 20. Observation Study In an observational study, investigators assess health outcomes in groups of participants according to a research plan or protocol. Participants may receive interventions (which can include medical products such as drugs or devices) or procedures as part of their routine medical care, but participants are not assigned to specific interventions by the investigator (as in a clinical trial). For example, investigators may observe a group of older adults to learn more about the effects of different lifestyles on cardiac health.
- 21. Reasons for Conducting Clinical Studies • Evaluating one or more interventions (for example, drugs, medical devices, approaches to surgery or radiation therapy) for treating a disease, syndrome, or condition • Finding ways to prevent the initial development or recurrence of a disease or condition. These can include medicines, vaccines, or lifestyle changes, among other approaches. • Evaluating one or more interventions aimed at identifying or diagnosing a particular disease or condition • Examining methods for identifying a condition or the risk factors for that condition • Exploring and measuring ways to improve the comfort and quality of life through supportive care for people with a chronic illness
- 22. Participating in Clinical Studies A clinical study is conducted according to a research plan known as the protocol. The protocol is designed to answer specific research questions and safeguard the health of participants. It contains the following information: • The reason for conducting the study • Who may participate in the study (the eligibility criteria) • The number of participants needed • The schedule of tests, procedures, or drugs and their dosages • The length of the study • What information will be gathered about the participants
- 23. Who Can Participate in a Clinical Study? Clinical studies have standards outlining who can participate. These standards are called eligibility criteria and are listed in the protocol. Some research studies seek participants who have the illnesses or conditions that will be studied, other studies are looking for healthy participants, and some studies are limited to a predetermined group of people who are asked by researchers to enroll. • Eligibility. The factors that allow someone to participate in a clinical study are called inclusion criteria, and the factors that disqualify someone from participating are called exclusion criteria. They are based on characteristics such as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions.
- 24. How Are Participants Protected? Informed consent is a process used by researchers to provide potential and enrolled participants with information about a clinical study. This information helps people decide whether they want to enroll or continue to participate in the study. The informed consent process is intended to protect participants and should provide enough information for a person to understand the risks of, potential benefits of, and alternatives to the study. In addition to the informed consent document, the process may involve recruitment materials, verbal instructions, question-and-answer sessions, and activities to measure participant understanding. In general, a person must sign an informed consent document before joining a study to show that he or she was given information on the risks, potential benefits, and alternatives and that he or she understands it. Signing the document and providing consent is not a contract.
- 25. Institutional review boards. Each conducted clinical study and each study of a drug, biological product, or medical device must be reviewed, approved, and monitored by an institutional review board (IRB). An IRB is made up of health practitioner, researchers, and members of the community. Its role is to make sure that the study is ethical and that the rights and welfare of participants are protected. This includes making sure that research risks are minimized and are reasonable in relation to any potential benefits, among other responsibilities. The IRB also reviews the informed consent document. In addition to being monitored by an IRB, some clinical studies are also monitored by data monitoring committees (also called data safety and monitoring boards).
- 26. NON-INTERVENTION STUDIES • Exploratory studies • Descriptive studies • Comparative (analytical) studies
- 27. Exploratory studies Is defined as a research used to investigate a problem which is not clearly defined. It is conducted to have a better understanding of the existing problem, but will not provide conclusive results. For such a research, a researcher starts with a general idea and uses this research as a medium to identify issues, that can be the focus for future research. An important aspect here is that the researcher should be willing to change his/her direction subject to the revelation of new data or insight. Such a research is usually carried out when the problem is at a preliminary stage. It is often referred to as grounded theory approach or interpretive research as it used to answer questions like what, why and how.
- 28. Types and methodologies of Exploratory research • While it may sound a little difficult to research something that has very little information about it, there are several methods which can help a researcher figure out the best research design, data collection methods and choice of subjects. • There are two ways in which research can be conducted namely primary and secondary. Under these two types, there are multiple methods which can used by a researcher. • The data gathered from these research can be qualitative or quantitative.
- 29. Some of the most widely used research designs include the following: Primary research methods Primary research is information gathered directly from the subject. It can be through a group of people or even an individual. Such a research can be carried out directly by the researcher himself or can employ a third party to conduct it on their behalf. Primary research is specifically carried out to explore a certain problem which requires an in-depth study.
- 30. • Surveys/polls: Surveys/polls are used to gather information from a predefined group of respondents. It is one of the most important quantitative method. • Various types of surveys or polls can be used to explore opinions, trends, etc. With the advancement in technology, surveys can now be sent online and can be very easy to access. • For instance, use of a survey app through tablets, laptops or even mobile phones. This information is also available to the researcher in real time as well. Nowadays, most organizations offer short length surveys and rewards to respondents, in order to achieve higher response rates. • For example: A survey is sent to a given set of students on assessment of the knowledge, attitude and perception of COVID-19 vaccine. Based on such information pharmaceutical organization can dig deeper into the topic and make business related decision.
- 31. Interviews: While you may get a lot of information from public sources, but sometimes an in person interview can give in-depth information on the subject being studied. Such a research is a qualitative research method. An interview with a subject matter expert can give you meaningful insights that a generalized public source won’t be able to provide. Interviews are carried out in person or on telephone which have open-ended questions to get meaningful information about the topic. For example: An interview with an employee can give you more insights to find out the degree of job satisfaction, or an interview with a subject matter expert of quantum theory can give you in-depth information on that topic.
- 32. Focus groups: Focus group is yet another widely used method in exploratory research. In such a method a group of people is chosen and are allowed to express their insights on the topic that is being studied. Although, it is important to make sure that while choosing the individuals in a focus group they should have a common background and have comparable experiences. For example: A focus group helps a research identify the opinions of consumers if they were to buy a phone. Such a research can help the researcher understand what the consumer value while buying a phone. It may be screen size, brand value or even the dimensions. Based on which the organization can understand what are consumer buying attitudes, consumer opinions, etc.
- 33. Observations: Observation research can be qualitative observation or quantitative observation. Qualitative observations are made when you use your senses to observe the results. (Sight, smell, touch, taste and hear.) Quantitative observations are made with instruments such as rulers, balances, graduated cylinders, beakers, and thermometers. These results are measurable. Such a research is done to observe a person and draw the finding from their reaction to certain parameters. In such a research, there is no direct interaction with the subject. • For example: Contribution of Different Risk Factors in the Occurrence of Stroke • The researcher observes the customers first reaction and collects the data, which is then used to draw inferences from the collective information.
- 34. Secondary research methods • Secondary research is gathering information from previously published primary research. In such a research you gather information from sources likes case studies, magazines, newspapers, books, etc. • Online research: In today’s world, this is one of the fastest way to gather information on any topic. • A lot of data is readily available on the internet and the researcher can download it whenever he needs it. • An important aspect to be noted for such a research is the genuineness and authenticity of the source websites that the researcher is gathering the information from. • For example: A researcher needs to find out what is the percentage of people that prefer a specific brand phone. The researcher just enters the information he needs in a search engine and gets multiple links with related information and statistics.
- 35. • Literature research: Literature research is one of the most inexpensive method used for discovering a hypothesis. There is tremendous amount of information available in libraries, online sources, or even commercial databases. Sources can include newspapers, magazines, books from library, documents from government agencies, specific topic related articles, literature, Annual reports, published statistics from research organizations and so on. • However, a few things have to be kept in mind while researching from these sources. Government agencies have authentic information but sometimes may come with a nominal cost. Also, research from educational institutions is generally overlooked, but in fact educational institutions carry out more number of research than any other entities. • Furthermore, commercial sources provide information on major topics like political agendas, demographics, financial information, market trends and information, etc.
- 36. • For example: A company has low sales for a drug. It can be easily explored from available statistics and market literature if the problem is market related or organization related or if the topic being studied is regarding financial situation of the country, then research data can be accessed through government documents or commercial sources. • Case study research: Case study research can help a researcher with finding more information through carefully analyzing existing cases which have gone through a similar problem. Such analysis are very important and critical especially in today’s health research. • The researcher just needs to make sure he analyses the case carefully in regards to all the variables present in the previous case against his own case. It is very commonly used by business organizations or social sciences sector or even in the health sector.
- 37. • For example: A particular orthopedic surgeon has the highest success rate for performing knee surgeries. A lot of other hospitals or doctors have taken up this case to understand and benchmark the method in which this surgeon does the procedure to increase their success rate.
- 38. • Exploratory research: Steps to conduct a research • Identify the problem: A researcher identifies the subject of research and the problem is addressed by carrying out multiple methods to answer the questions. • Create the hypothesis: When the researcher has found out that there are no prior studies and the problem is not precisely resolved, the researcher will create a hypothesis based on the questions obtained while identifying the problem. • Further research: Once the data has been obtained, the researcher will continue his study through descriptive investigation. Qualitative methods are used to further study the subject in detail and find out if the information is true or not.
- 39. Characteristics of Exploratory research • They are not structured studies • It is usually low cost, interactive and open ended. • It will enable a researcher answer questions like what is the problem? What is the purpose of the study? And what topics could be studied? • To carry out exploratory research, generally there is no prior research done or the existing ones do not answer the problem precisely enough. • It is a time consuming research and it needs patience and has risks associated with it. • The researcher will have to go through all the information available for the particular study he is doing.
- 40. Advantages of Exploratory research • The researcher has a lot of flexibility and can adapt to changes as the research progresses. • It is usually low cost. • It helps lay the foundation of a research, which can lead to further research. • It enables the researcher understand at an early stage, if the topic is worth investing the time and resources and if it is worth pursuing. • It can assist other researchers to find out possible causes for the problem, which can be further studied in detail to find out, which of them is the most likely cause for the problem.
- 41. Disadvantages of Exploratory research Even though it can point you in the right direction towards what is the answer, it is usually inconclusive. The main disadvantage of exploratory research is that they provide qualitative data. Interpretation of such information can be judgmental and biased. Most of the times, exploratory research involves a smaller sample, hence the results cannot be accurately interpreted for a generalized population. Many a times, if the data is being collected through secondary research, then there is a chance of that data being old and is not updated.
- 42. Importance of Exploratory research Exploratory research is carried out when a topic needs to be understood in depth, especially if it hasn’t been done before. The goal of such a research is to explore the problem and around it and not actually derive a conclusion from it. Such kind of research will enable a researcher to set a strong foundation for exploring his ideas, choosing the right research design and finding variables that actually are important for the analysis. Most importantly, such a research can help organizations or researchers save up a lot of time and resources, as it will enable the researcher to know if it worth pursuing.
- 43. Descriptive Studies Descriptive studies are observational studies which describe the patterns of disease occurrence in relation to variables such as person, place and time. They are often the first step or initial enquiry into a new topic, event, disease or condition. Descriptive studies can be divided into two roles - those studies that emphasize features of a new condition and those which describe the health status of communities or populations. Case reports, case-series reports, before-and-after studies, cross-sectional studies and surveillance studies deal with individuals. Ecological Studies examine populations.
- 44. • Common misuses of descriptive studies involve a lack of a clear, specific and reproducible case definition and establishing a casual relationship which the data cannot support. • Whilst descriptive studies can highlight associations between variables or between exposure and outcome variables, they cannot establish causality. • Descriptive studies do not have a comparison (control) group which means that they do not allow for inferences to be drawn about associations, casual or otherwise. • However, they can suggest hypotheses which can be tested in analytical observational studies.
- 45. Uses of Descriptive Studies 1. Health care planning Descriptive studies provide knowledge about which populations or subgroups are most or least affected by disease. This enables public health administrators to target particular segments of the population for education or prevention programmes and can help allocate resources more efficiently. 2. Hypothesis generation Descriptive studies identify descriptive characteristics which frequently constitutes an important first step in the search for determinants or risk factors that can be altered or eliminated to reduce or prevent disease.
- 46. Types of Descriptive Studies Case reports Case reports describe the experience of a single patient or a group of patients with a similar diagnosis. These types of studies typically depict an observant clinician identifying an unusual feature of a disease or a patient's history. They can represent the first clues in the identification of new diseases or adverse effects of an exposure. A case report can prompt further investigations with more rigorous study design. Case reports are quite common in medical journals. A systematic review found that they accounted for over one third of all articles published. They are useful to public health as they can provide an interface between clinical medicine and epidemiology.
- 47. Case Series A case series is a report that describes clinical findings seen in a succession of patients who seem to display a similar condition or an outcome of interest. Another way of defining a case series is that case series are collections of individual case reports which may occur within a fairly short period of time and these are aggregated into one publication. No control group is involved. Something unexpected has been observed - e.g. more cases than usual of a rare disorder or new signs and symptoms of an emerging disease - hence the motivation to write it up and share it with the wider clinical community.
- 48. • This study design has historical importance in epidemiology. It was often used as an early means to identify the begining or presence of an epidemic. • Even now, the routine surveillance of accumulating case reports often suggest the emergence of a new disease or epidemic. A convenient feature of case-series is that they can provide a case group for a case- control study. • An advantage of case series over case report is that a case series can help formulate a new and useful hypothesis rather than merely documenting an interesting medical oddity. However, its disadvantage is that it cannot be used to test for the presence of a valid statistical association.
- 49. • Cross-sectional (Prevalence) Study • This is the observation of a defined population at a single point in time or time interval. Exposure and outcome are determined simultaneously. • The cross-sectional study describes the presence and/or absence of various clinical features, so it provides a cross-sectional comparison. This means that costs are small and loss to follow up is not a problem. • However, because exposure and outcome are measured at the same time point, the temporal sequence is often impossible to determine. Sometimes the cross- sectional study can be considered an analytic study, when it is used to test an epidemiologic hypothesis. • This can only occur when the current values of the exposure variables are unaltered over time, thus representing the value present at the initiation of the disease. For example, factors at birth.
- 50. • The cross-sectional survey is sometimes referred to as a prevalence study and it can survey or assess the health status of a population - e.g. Health Survey of Ghana. • A survey can be defined as a special inquiry which collects planned information from individuals (usually a sample) about their history, habits, knowledge, attitudes or behaviour. • The principles involved include sampling, instrument design, non-response and accuracy. • Reasons for non-response incorporate the effect of the topic, study design (postal, telephone or face-to-face interviews), age, sex, social class, urban/rural location and general attitudes to survey. See entry on Survey in Toolkit for more details. • It is worth noting that the term 'cross-sectional' study is also used in social research. Here, the cross-sectional study refers to a snapshot of a population at a particular point in time. • This contrasts with longitudinal studies which follow a population over a period of time, where one population is compared with another within the same country and cross- national, where one country population is compared with other countries.
- 51. • Ecological Study (or Ecological Correlational Study) • Ecological correlational studies look for associations between exposures and outcomes in populations rather than in individuals. They use data that has already been collected. • This could be argued to be a form of what social scientists call secondary statistical analysis. The measure of association between exposure and outcome is the correlation coefficent r. • This is a measure of how linear the relationship is between the exposure and outcome variables. (Note that correlational is a specific form of association and requires two continuous variables).
- 52. • Advantages of an ecological study 1.An ecological study is quick and cheap to conduct. 2.It can generate new hypotheses. 3.It can identify new risk factors. • Disadvantages of an ecological study 1.It is unable to control for confounding factors. This is often referred to as 'ecological fallacy', where two variables seem to be correlated but their relationship is in fact affected by cofounding factor(s). 2.It cannot link exposure with disease in individuals as those with disease may not be expose. 3.Its use of average exposure levels masks more complicated relationships with disease. 4.Its units of study are populations not individuals. Therefore, the disease rates linked with population characteristics and the association observed at group level does not reflect association at individual level.
- 53. Case-control Study • A case-control study is designed to help determine if an exposure is associated with an outcome (i.e., disease or condition of interest). In theory, the case-control study can be described simply. • First, identify the cases (a group known to have the outcome) and the controls (a group known to be free of the outcome). • Then, look back in time to learn which subjects in each group had the exposure(s), comparing the frequency of the exposure in the case group to the control group.
- 54. • By definition, a case-control study is always retrospective because it starts with an outcome then traces back to investigate exposures. • When the subjects are enrolled in their respective groups, the outcome of each subject is already known by the investigator. • This, and not the fact that the investigator usually makes use of previously collected data, is what makes case-control studies ‘retrospective’.
- 55. • Advantages of Case-Control Studies • Case-control studies have specific advantages compared to other study designs. They are comparatively quick, inexpensive, and easy. • They are particularly appropriate for • (1) investigating outbreaks, and • (2) studying rare diseases or outcomes. • An example of (1) would be a study of endophthalmitis following ocular surgery. When an outbreak is in progress, answers must be obtained quickly. • An example of (2) would be a study of risk factors for uveal melanoma, or corneal ulcers.
- 56. • Since case-control studies start with people known to have the outcome (rather than starting with a population free of disease and waiting to see who develops it) it is possible to enroll a sufficient number of patients with a rare disease. • The practical value of producing rapid results or investigating rare outcomes may outweigh the limitations of case-control studies. • Because of their efficiency, they may also be ideal for preliminary investigation of a suspected risk factor for a common condition; conclusions may be used to justify a more costly and time-consuming longitudinal study later. Cases • Consider a situation in which a large number of cases of post-operative endophthalmitis have occurred in a few weeks. The case group would consist of all those patients at the hospital who developed post-operative endophthalmitis during a pre-defined period.
- 57. • The definition of a case needs to be very specific: • Within what period of time after operation will the development of endophthalmitis qualify as a case – one day, one week, or one month? • Will endophthalmitis have to be proven microbiologically, or will a clinical diagnosis be acceptable? • Clinical criteria must be identified in great detail. If microbiologic facilities are available, how will patients who have negative cultures be classified? • How will sterile inflammation be differentiated from endophthalmitis? • There are not necessarily any ‘right’ answers to these questions but they must be answered before the study begins. At the end of the study, the conclusions will be valid only for patients who have the same sort of ‘endophthalmitis’ as in the case definition.
- 58. Controls • Controls should be chosen who are similar in many ways to the cases. The factors (e.g., age, sex, time of hospitalization) chosen to define how controls are to be similar to the cases are the ‘matching criteria’. • The selected control group must be at similar risk of developing the outcome; it would not be appropriate to compare a group of controls who had traumatic corneal lacerations with cases who underwent elective intraocular surgery. • In our example, controls could be defined as patients who underwent elective intraocular surgery during the same period of time.
- 59. Matching Cases and Controls • Although controls must be like the cases in many ways, it is possible to over-match. Over-matching can make it difficult to find enough controls. Also, once a matching variable has been selected, it is not possible to analyse it as a risk factor. • Matching for type of intraocular surgery (e.g., secondary IOL implantation) would mean including the same percentage of controls as cases who had surgery to implant a secondary IOL; if this were done, it would not be possible to analyse secondary IOL implantation as a potential risk factor for endophthalmitis. • An important technique for adding power to a study is to enroll more than one control for every case. For statistical reasons, however, there is little gained by including more than two controls per case.
- 60. • Collecting Data • After clearly defining cases and controls, decide on data to be collected; the same data must be collected in the same way from both groups. • Care must be taken to be objective in the search for past risk factors, especially since the outcome is already known, or the study may suffer from researcher bias. • Although it may not always be possible, it is important to try to mask the outcome from the person who is collecting risk factor information or interviewing patients.
- 61. • An odds ratio without a confidence interval is not very meaningful. These calculations are usually made with computer programmes (e.g., Epi-Info). Case-control studies cannot provide any information about the incidence or prevalence of a disease because no measurements are made in a population based sample. Risk Factors and Sampling • Another use for case-control studies is investigating risk factors for a rare disease, such as uveal melanoma. In this example, cases might be recruited by using hospital records. Patients who present to hospital, however, may not be representative of the population who get melanoma. • If, for example, women present less commonly at hospital, bias might occur in the selection of cases.
- 62. • The selection of a proper control group may pose problems. A frequent source of controls is patients from the same hospital who do not have the outcome. • However, hospitalised patients often do not represent the general population; they are likely to suffer health problems and they have access to the health care system. • An alternative may be to enroll community controls, people from the same neighborhoods as the cases. Care must be taken with sampling to ensure that the controls represent a ‘normal’ risk profile. • Sometimes researchers enroll multiple control groups. These could include a set of community controls and a set of hospital controls. • Confounders Matching controls to cases will mitigate the effects of confounders. A confounding variable is one which is associated with the exposure and is a cause of the outcome. If exposure to toxin ‘X’ is associated with melanoma, but exposure to toxin ‘X’ is also associated with exposure to sunlight (assuming that sunlight is a risk factor for melanoma), then sunlight is a potential confounder of the association between toxin ‘X’ and melanoma.
- 63. Case-Control Studies: Advantages and Disadvantages • ADVANTAGES can obtain findings quickly • can often be undertaken with minimal funding efficient for rare diseases can study multiple exposures • generally requires few study subjects
- 64. Case-Control Studies: Advantages and Disadvantages • DISADVANTAGES cannot generate incidence data subject to bias difficult if record keeping is either inadequate or unreliable • selection of controls can be difficult
- 65. Cohort studies • Cohort studies are a type of medical research used to investigate the causes of disease and to establish links between risk factors and health outcomes. • The word cohort means a group of people. These types of studies look at groups of people. They can be forward-looking (prospective) or backward-looking (retrospective). • Prospective” studies are planned in advance and carried out over a future period of time.
- 66. • Retrospective cohort studies look at data that already exist and try to identify risk factors for particular conditions. Interpretations are limited because the researchers cannot go back and gather missing data. • These long-term studies are sometimes called longitudinal studies. Fast facts on cohort studies • Cohort studies typically observe large groups of individuals, recording their exposure to certain risk factors to find clues as to the possible causes of disease. • They can be prospective studies and gather data going forward, or retrospective cohort studies, which look at data already collected. • The Nurses’ Health Study is one example of a large cohort study, and it has produced many important links between lifestyle choices and health by following hundreds of thousands of women across Ghana. • Such research can also help identify social factors that influence health.
- 67. Limitations • They are less suited to finding clues about rare diseases. A case-control study identifies cases of disease first and then analyzes exposure to risk factors, whereas cohort studies follow exposure data and watch for any emerging cases of disease. • · They are typically unsuitable for identifying the causes of a sudden outbreak of disease. • A case-control study can give quicker results. • · They are expensive to run and usually take many years, often decades, to produce results. • Participants may leave the cohort, perhaps move away, lose touch, or die from a cause that is not being studied. This can bias the results.
- 68. Observational study designs • Observational studies are ones where researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to change who is or isn’t exposed to it • It include ecological designs, cross sectional, case-control, case-crossover, retrospective and prospective cohorts. • An important subset of observational studies is diagnostic study designs, which evaluate the accuracy of diagnostic procedures and tests as compared to other diagnostic measures. • These include diagnostic accuracy designs, diagnostic cohort designs, and diagnostic randomized controlled trials.
- 69. INTERVENTIONAL STUDIES • Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease. • Each study design has specific outcome measures that rely on the type and quality of data utilized. • There are two categories of intervention studies: • experimental studies and • quasi-experimental studies.
- 70. EXPERIMENTAL STUDIES • Experimental studies are ones where researchers introduce an intervention and study the effects. Experimental studies are usually randomized, meaning the subjects are grouped by chance. • Randomized controlled trial (RCT): Eligible people are randomly assigned to one of two or more groups. One group receives the intervention (such as a new drug) while the control group receives nothing or an inactive placebo. • The researchers then study what happens to people in each group. Any difference in outcomes can then be linked to the intervention.
- 71. Quasi-experimental research • quasi-experimental design aims to establish a cause-and-effect relationship between an independent and dependent variable. • However, unlike a true experiment, a quasi-experiment does not rely on random assignment. Instead, subjects are assigned to groups based on non-random criteria. • Quasi-experimental design is a useful tool in situations where true experiments cannot be used for ethical or practical reasons.
- 72. CONCLUSIONS • Statistical conclusion validity is the degree to which conclusions about the relationship among variables based on the data are correct or "reasonable". This began as being solely about whether the statistical conclusion about the relationship of the variables was correct, but now there is a movement towards moving to "reasonable" conclusions that use: quantitative, statistical, and qualitative data. • two types of errors can occur: • type I :finding a difference or correlation when none exists • type II :finding no difference or correlation when one exists.
- 73. Internal validity refers specifically to whether an experimental treatment/condition makes a difference or not, and whether there is sufficient evidence to support the claim. External validity refers to the generalizibility of the treatment/condition outcomes. History--the specific events which occur between the first and second measurement. Maturation--the processes within subjects which act as a function of the passage of time. i.e. if the project lasts a few years, most participants may improve their performance regardless of treatment. Testing--the effects of taking a test on the outcomes of taking a second test. Instrumentation--the changes in the instrument, observers, or scorers which may produce changes in outcomes. Statistical regression--It is also known as regression to the mean. This threat is caused by the selection of subjects on the basis of extreme scores or characteristics. Give me forty worst students and I guarantee that they will show immediate improvement right after my treatment. • Selection of subjects--the biases which may result in selection of comparison groups. Randomization (Random assignment) of group membership is a counter-attack against this threat.
- 74. WAYS TO ENSURE VALIDITY OF A RESEARCH 1. Triangulation facilitates validation of data through cross verification from more than two sources. • It tests the consistency of findings obtained through different instruments and increases the chance to control, or at least assess, some of the threats or multiple causes influencing our results.
- 75. • There are several types of bias encountered in research, and triangulation can help with most of them. • Measurement bias is caused by the way in which you collect data. Triangulation allows you to combine individual and group research options to help reduce bias such as peer pressure on focus group participants. • Sampling bias is when you don’t cover all of the population you’re studying or you cover only some parts because it’s more convenient Triangulation combines the different strengths of these options to ensure you getting sufficient coverage. • Procedural bias occurs when participants are put under some kind of pressure to provide information. For example, doing “vox pop” style interrupt polls might catch the participants unaware and thus affect their answers.
- 76. 2. Control groups are essential to experimental design. When researchers are interested in the impact of a new treatment, they randomly divide their study participants into at least two groups: • The treatment group (also called the experimental group) receives the treatment whose effect the researcher is interested in. • The control group receives either no treatment, a standard treatment whose effect is already known, or a placebo (a fake treatment). • The treatment is any independent variable manipulated by the experimenters, and its exact form depends on the type of research being performed. In a medical trial, it might be a new drug or therapy. In public policy studies, it could be a new social policy that some receive and not others.
- 77. 3. Pre-testing is the administration of the data collection instrument with a small set of respondents from the population for the full scale survey. If problems occur in the pre-test, it is likely that similar problems will arise in full-scale administration. • The purpose of pre-testing is to identify problems with the data collection instrument and find possible solutions. • It is not possible to anticipate all of the problems that will be encountered during data collection. Terminology used in questionnaires or interviews may not be understood by respondents and information to be retrieved from documents may not be readily available. Reducing error to acceptable levels requires the pre- testing of data collection instruments.
- 78. Study Design • The selection of a study design is the most critical step in the research methodology. • Crucial factors should be considered during the selection of the study design, which is the formulated research question, as well as the method of participant selection. • Different study designs can be applied to the same research question(s). • Research designs are classified as qualitative, quantitative, and mixed design. • Observational design occupies the middle and lower parts of the hierarchy of evidence-based pyramid. The observational design is subdivided into descriptive, including cross-sectional, case report or case series, and correlational, and analytic which includes cross-section, case-control, and cohort studies.
- 79. Qualitative Study Design • Qualitative research design varies depending upon the method used; participant observations, in-depth interviews (face-to-face or on the telephone), and focus groups are all examples of methodologies which may be considered during qualitative research design. Although there is diversity in the various qualitative methodologies, there are also commonalities between them. The underlying reason for carrying out any qualitative research is to gain a richly detailed understanding of a particular topic, issue, or meaning based on first-hand experience. This is achieved by having a relatively small but focused sample base because collecting the data can be rather time consuming; qualitative data is concerned with depth as opposed to quantity of findings. A qualitative research design is concerned with establishing answers to the whys and hows of the phenomenon in question (unlike quantitative).
- 80. QUANTITATIVE Quantitative methods emphasize objective measurements and the statistical, mathematical, or numerical analysis of data collected through polls, questionnaires, and surveys, or by manipulating pre-existing statistical data using computational techniques. Quantitative research focuses on gathering numerical data and generalizing it across groups of people or to explain a particular phenomenon.
- 81. This research design is to determine the relationship between one thing [an independent variable] and another [a dependent or outcome variable] within a population. It is either descriptive [subjects usually measured once] or experimental [subjects measured before and after a treatment]. It also deals in numbers, logic, and an objective stance. Quantitative research focuses on numeric and unchanging data and detailed, convergent reasoning rather than divergent reasoning [i.e., the generation of a variety of ideas about a research problem in a spontaneous, free-flowing manner].
- 82. MIXED METHODS • The term “mixed methods” refers to an emergent methodology of research that advances the systematic integration, or “mixing,” of quantitative and qualitative data within a single investigation or sustained program of inquiry. • Mixed methods can be use in the social sciences, health and medical sciences including fields such as nursing, family medicine, social work, mental health, pharmacy, allied health researches.
- 83. The core characteristics of a well-designed mixed methods study in research include the following: 1.Collecting and analyzing both quantitative (closed-ended) and qualitative (open- ended) data. 2.Using rigorous procedures in collecting and analyzing data appropriate to each method’s tradition, such as ensuring the appropriate sample size for quantitative and qualitative analysis. 3.Integrating the data during data collection, analysis, or discussion. 4.Using procedures that implement qualitative and quantitative components either concurrently or sequentially, with the same sample or with different samples. 5.Framing the procedures within philosophical/theoretical models of research, such as within a social constructionist model that seeks to understand multiple perspectives on a single issue for example, what patients, caregivers, clinicians, and practice staff would characterize as “high quality treatment” in medical field.