– Scale: 0 - 100 • What is the temperature today? – Scale: Celsius or Fahrenheit 36
13 There are 4 types of primary scales Primary Scales Nominal Ordinal Interval Ratio Categorical Metric 37 • Nominal scale – no rank-ordering between values – Example: Which one of the following media influences your purchasing decisions the most? 1. TV 2. Radio 3. Newspaper • Ordinal scale – rank ordering between values – Example: Which of the following describes your level of education (please circle the number on the left) 1. Did not complete high school 2. High school graduate 3. Some College 4. College graduate 5. Postgraduate degree Categorical scales: nominal vs. ordinal scale 38 Examples of categorical questions and scales used Nominal Scale Ordinal Scale Nominal Scale Ordinal Scale 39
14 • This includes all the examples of metric questions we used earlier in this week’s lecture • Interval scale is a type of metric scale – You can talk about “average customer satisfaction”, or “average importance rating”, and etc • Examples of other types of interval scales – temperature (Fahrenheit or Celsius) Interval scale - most measures of the strength of feelings, emotions, attitude and beliefs are based on an interval scale 40 There is one scale that we have left out in our lecture so far: ratio Scale • You use ratio scale to provide exact quantity measures of tangible things • Example: What is your annual income before taxes? ___ What makes a ratio scale and how does it differentiate from interval scale? • A natural, unambiguous 0 (e.g., $0) 41 Ratio Scale Examples 42
15 The science behind how different scales are classified - whether they exhibit three properties Properties Description Order property Establish ‘relative magnitude’ to rank order objects e.g. 1st−2nd−3rd; 90 kg > 60 kg; frequent vs infrequent Distance property Absolute differences between objects e.g. (six children – three children) = three children; income (in $); age (in years) Origin property Unique descriptor for ‘true state of nothing’ e.g., asking height or age; number of times to shop during a week; market share 43 Primary scales - summary No 44 Scale is chosen by you the researcher, so it is possible for the same variable to be measured by different primary scales Example • Which of the following describes your annual income before tax (please circle the number on the left) 1. <$20,000 2. $20,000 to <$50,000 3. $50,000 to <$80,000 4. $80,000 to <$120,000 5. $120,000 and above Or • What is your annual income before taxes? ___ Ordinal scale, so income data thus collected is categorical Ratio scale, so income data thus collected is metric 45
16 Recap: 4 types of primary scales Primary Scales Nominal Ordinal Interval Ratio Categorical Metric 46 Recap: the dichotomy of categorical vs. metric Categorical Questions Categorical Data Categorical Scale Metric Questions Metric Data Metric Scale 47 • Metric – data that you can add, subtract, and compute averages for • Categorical – can NOT add, subtract, or compute averages for (even if it is coded as numbers, such as in marital status on the previous page) This is an important distinction because comparative research questions entail comparing these averages.
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