Home > Scale (social sciences)
Scaling is the measurement of a variable in such a way that it can be expressed on a continuum. Rating your preference for a product from 1 to 10 is an example of a scale. With comparative scaling, the items are directly compared with each other (example : Do you prefer Pepsi or Coke?). In noncomparative scaling each item is scaled independently of the others (example : How do you feel about Coke?).
1 Composite measures
Indexes are similar to scales except multiple indicators of a variable are combined into a single measure. The index of consumer confidence, for example, is a combination of several measures of consumer attitudes. A typology is similar to an index except the variable is measured at the nominal level. Scaling, indexes, and typologies are all examples of composite measures.
2 Data types
The type of information collected can influence scale construction. Different types of information are measured in different ways.
- Some data is measured at the nominal level. That is, any numbers used are mere labels : they express no mathematical properties. Examples are SKU inventory codes and UPC bar codes.
- Some data is measured at the ordinal level. Numbers indicate the relative position of items, but not the magnitude of difference. An example is a preference ranking.
- Some data is measured at the interval level. Numbers indicate the magnitude of difference between items, but there is no absolute zero point. Examples are attitude scales and opinion scales.
- Some data is measured at the ratio level. Numbers indicate magnitude of difference and there is a fixed zero point. Ratios can be calculated. Examples include: age, income, price, costs, sales revenue, sales volume, and market share.
3 Scale construction decisions
~ What level of data is involved (nominal, ordinal, interval, or ratio)?
~ What will the results be used for?
~ Should you use a scale, index, or typology?
~ What types of statistical analysis would be useful?
~ Should you use a comparative scale or a noncomparative scale?
~ How many scale divisions or categories to use (1 to 10; 1 to 7; -3 to +3)?
~ Odd or even number of divisions - odd gives neutral center value; even forces respondents to take a non-neutral position
~ The nature and descriptiveness of the scale labels?
~ The physical form or layout of the scale? (graphic, simple linear, verticle, horizontal)
~ Forced versus optional response?
4 Comparative scaling techniques
- Paired comparison scaling - a respondent is presented with two items at a time and asked to select one (example : Do you prefer Pepsi or Coke?). This is an ordinal level technique.
- Rank-order scaling - a respondent is presented with several items simultaneously and asked to rank them (example : Rate the following advertisements from 1 to 10.). This is an ordinal level technique.
- Constant sum scaling - a respondent is given a constant sum of money, script, credits, or points and asked to allocate these to various items (example : If you had 100 Yen to spend on food products, how much would you spend on product A, on product B, on product C, etc.). This is an ordinal level technique.
- Bogardus social distance scaling - measures the degree to which a person is willing to associate with a class or type of people. It asks how willing the respondent is to make various associations. The results are reduced to a single score on a scale. There are also non-comparative versions of this scale.
- Q-Sort scaling - Up to 140 items are sorted into groups based a rank-order procedure.
- Guttman scaling - This is a procedure to determine whether a set of items can be rank-ordered on an unidimensional scale. It utilizes the intensity structure among several indicators of a given variable. Statements are listed in order of importance. The rating is scaled by summing all responses until the first negative response in the list.
5 Non-comparative scaling techniques
- Continuous rating scale (also called the graphic rating scale) - respondents rate items by placing a mark on a line. The line is usually labeled at each end. There are sometimes a series of numbers, called scale points, (say, from zero to 100) under the line. Scoring and codification is difficult.
- Likert Scaling - Respondents are asked to indicate the amount of agreement or disagreement (from strongly agree to strongly disagree) on a five-point scale. The same format is used for multiple questions.
- Semantic differential scaling - Respondents are asked to rate on a 7 point scale an item on various attributes. Each attribute requires a scale with bipolar terminal labels.
- Stapel scaling - This is a unipolar ten-point rating scale. It ranges from +5 to -5 and has no neutral zero point.
- Thurstone scaling - This is a scaling technique that incorporates the intensity structure among indicators.
- Mathematically derived scaling - Researchers infer respondents’ evaluations mathematically. Two examples are multi dimensional scaling and conjoint analysis.
