ERRORS IN RESEARCH DESIGN
- 1. ERRORS IN RESEARCH DESIGN Course instructor: Presented by: Dr. Vijay Kumar S V Singh ID-
- 2. CONTENT • Introduction • Component of errors • Type of errors • Features of good research • Conclusion
- 3. Introduction At all stages, from problem formulation to report presentation– errors can arise. It is rare that a research project will be error free. Errors in research design can be cause of Research errors. Consequently the research designer must adopt a strategy for managing and maintaining the error .
- 4. Components of errors Provide information that is to be accurate and error free as possible. Total error has two distinct components: Total Error = Sampling Error + Non Sampling Error Total error is usually measured as total error variance also know as the mean squared error: (Total Error) = (Sampling Error ) + (Non Sampling Error )
- 5. Types of errors 1. Population Specification Error: I t is defined as the “non correspondence of the required population to the population selected by the investigator” . It occurs when a researcher selects an inappropriate population from which to obtain data. For example many times package goods manufacturers conduct surveys amongst housewive- because they are easy to contact and because it is assumed that as they are the end users they make the purchase decisions.
- 6. 2. Sampling Error: It is defined as the “non correspondence of sample selected by probability means and the representative sample selected by the researcher” It occurs when a probability sampling method is used to select a sample and this sample is not representative of the population concerned. For example, a random sample of 500 people composed only of people between 35-50 years of age may not be representative of adult population. Sampling error is affected by the homogeneity of the population under study. In general – more homogenous the population; the smaller the sampling error.
- 7. 3. Selection Error: It is defined as the “Non correspondence of sample selected by non probability means and the representative sample sought by the researcher.” There is a natural tendency for the investigator to select those respondents who are most accessible and agreeable. Such samples are often comprised of friends and associates who more or less represent the desired population.
- 8. 4. Frame Error: I t is defined as the non-correspondence of the sought sample with the required sample. I t is usually a list - ing of all the elements that identify a population. For example a sampling frame that specifies the population as all adults using oral care products – may well leave out people who prefer using neem and babool sticks, homemade toothpaste and powders – leading to a frame error in defining the population.
- 9. 5. Non Response Error: A nonresponse error occurs, when the obtained sample differs from the original selected sample. Non response can occur in two ways – (a) Non-contact errors : Arise due to the inability to reach the respondent. This may be because the respondent is NAH (Not at Home). (b)Refusal errors: Arises when the respondent does not respond to a particular item or to multiple items of the questionnaire. Monthly Household Income, Religion, Sex and Politics are topics that may elicit item refusal – normally categorised as refused.
- 10. 6. Surrogate Information Error: This is defined as the non-correspondence of the information being sought by the researcher and that is required to solve the problem. in other words, information is obtained from subst itutes rather than original sample. The necessity to accept surrogate information arises from either the inability or the unwillingness of the respondent to provide the needed information.
- 11. 7. Measurement Error: This may be defined as the non correspondence of information obtained by measurement process and the information sought by the researcher. Such errors can potentially arise at any stage of the measurement process – from the development of the instrument till the analysis of findings. The error can also occur at transmittal stage - when the interviewer is questioning the respondent.
- 12. 8. Experimental Error: I t can be defined as the non correspondence of the “ t rue impact of” and the “impact at-tributed to” the independent variable. When an experiment is conducted, the researcher attempts to measure the impact of one or more manipulated independent variable on some dependent variable – while controlling the impact of exogenous variable. For example a study – trying to find out reasons for cancer may conclude that as all the patients under observation used to eat bread therefore eating bread is the cause of cancer.
- 13. Conclusion There are two basic approaches for reducing errors. 1. The first is to minimize errors through research design. 2. The second is to estimate and measure error. I n spite of all the precautions undertaken, not all errors – especially those related to fieldwork – would be eliminated. In such a situation if we can have an estimate of error we can say how accurate the research design was. However only sampling errors are measurable with some degree of confidence. Statistics help us to reduce the sampling error to a large degree but for non sampling error researchers still have to rely on their intuition.