SOURCES OF ERROR AND SCALES OF MEASUREMENT
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This document discusses different scales of measurement used in behavioral sciences research: nominal, ordinal, interval, and ratio scales. It provides examples of variables that fall under each scale. Nominal scales involve categorizing variables without rank. Ordinal scales involve ordering categories but without precise intervals between ranks. Interval scales have equal intervals between ranks and a true zero point. Ratio scales have all the properties of interval scales plus a meaningful zero point. The document also discusses sources of error in measurement, including issues related to respondents, measurers, and instruments.
SOURCES OF ERROR AND SCALES OF MEASUREMENT
- 1. MEASUREMENT TECHNIQUES AND SOURCES OF ERROR
- 2. ○ AHSAN ALI ○ AWAIS BHATTI ○ ALTAF JAMALI
- 3. Measurement Scales Four kinds of scale of measurement are important for quantifying variables in the behavioral sciences: 1. Nominal Scale 2. Ordinal Scale 3. Interval Scale 4. Ratio Scale
- 4. Nominal Scale ○ This type of scale allows a researcher to classify characteristics of the persons, places or objects into categories. ○ Sometimes variables measured on nominal scales are called categorical or qualitative. ○ Simply describes differences between things by assigning them into categories Examples: Group membership (1 = Experimental, 2=Placebo ) A person’s gender (0 = Female, 1 = Male) Blood type, marital status, religion
- 8. Ordinal Scale, Continued ○ Examples: Socioeconomic Status 1 = Low 2 = Middle 3 = High Health Status 1 = Poor 2 = Fair 3 = Good 4 = Excellent
- 10. 4. Ratio Scale ○ The most precise level of measurement consists of meaningfully ordered characteristics with equal intervals between them and the presence of a zero point that is not arbitrary but determined by nature. ○ For example, the zero point on a centimeter scale indicates complete absence of length or height, but absolute zero of temperature is theoretically unobtainable. ○ Represents the actual amount of variables ○ Examples: weight, height, income, distance etc. ○ All statistical techniques are usable.
- 11. Sources of error in measurement ○ Respondent: ● Reluctance ● Fatigue, boredom, anxiety etc. a. Situation:Any condition which places a strain on interview can have serious effects on the interviewer-respondent rapport. For instance, if someone else is present, he can distort responses by joining in or merely by being present. If the respondent feels that anonymity is not assured, he may be reluctant to express certain feelings. b. Measurer: ● Behaviour, style or look may encourage/discourage certain replies from respondents ● Incorrect coding ● Careless mechanical processing of data ● Faulty tabulation and/or statistical calculation etc. c. Instrument: ● complex words, ambiguous meaning, poor printing, inadequate space for replies etc.
- 12. ○ 7. The Ritz-Carlton Hotel used a customer opinion questionnaire to obtain performance data about its dining and entertainment services (The Ritz-Carlton Hotel, Naples, Florida, February 2006). Customers were asked to rate six factors: Welcome, Service, Food, Menu Appeal, Atmosphere, and Overall Experience. Data were recorded for each factor with 1 for Fair, 2 for Average, 3 for Good, and 4 for Excellent. ○ a. The customer responses provided data for six variables. Are the variables categorical or quantitative? ○ b. What measurement scale is used?
- 13. ○ 10. The Wall Street Journal (WSJ) subscriber survey (October 13, 2003) asked 46 questions about subscriber characteristics and interests. State whether each of the following questions provided categorical or quantitative data and indicate the measurement scale appropriate for each. ○ a. What is your age? ○ b. When did you first start reading the WSJ? High school, college, early career, midcareer, late career, or retirement? ○ c. Are you male or female? ○ d. How long have you been in your present job or position? ○ e. What type of vehicle are you considering for your next purchase? Nine response categories include sedan, sports car, SUV, minivan, and so on.