1. Chapter 6 Indexes, Scales, and Typologies

2. The terms index and scale are typically used imprecisely and interchangeably in social research literature.

3. Both scale and indexes are ordinal measures of variables.
Both rank-order the units of analysis in terms of specific variables such as religiosity, alienation, socioeconomic status, prejudice.

4. Both scales and indexes are composite measures of variables – that is, measurements based on more than one data item.

5. Eg. A survey respondent’s score on an index or scale of religiosity is determined by the response given to several questionnaire items, each of which provides some indication of religiosity

6. Index
An index is constructed by simply accumulating scores assigned to individual attributes. We might measure prejudice, for example, by adding up the number of prejudiced statements each respondent agreed with

7. Scale
A scale is constructed by assigning scores to patterns of responses, recognizing that some items reflect a relatively weak degree of the variable while others reflect something stronger
Scales are generally superior to indexes, because scales take into consideration the intensity with which different items reflect the variable being measured
Scale scores convey more information than index scores

8. Index Construction Selecting possible items
Examining their empirical relationships
Scoring the index
Validating it

9. Item Selection Face validity
the first criterion for selecting items to be included in the index is face validity (or logical validity).
if you want to measure political conservatism, for example, each of your items should appear on its face to indicate conservatism

10. Item Selection Unidimensionality
the methodological literature on conceptualization and measurement stresses the need for unidimensionality in scale and indexes construction
a composite measure should represent only one dimension of a concept

11. Item Selection General or Specific
the general dimension you’re attempting to measure may have many nuances
in the example of religiosity, the indicators – ritual participation, belief – represent different types of religiosity

12. Item Selection Variance
the amount of variance that is provided by items
to have variance, you have two options
first – you may select several items the responses to which divide people about equally in terms of the variable
second- select items differing in variance – one item might identify about half the subjects as conservative, while another might identify few of the respondents as conservatives

13. Examining of Empirical Relationships
Response to one question will help us predict how that respondent will answer on other questions
Bivariate relationships
Multivariate relationships

14. Index Scoring Decide the range of index scores
See how many cases, questions, for each point in the scale
Assigning scores for each particular response – usually weighted equally unless there is a reason for heavier weight for a case

15. Handling Missing Data Exclude the cases
Treat it as one of the existing responses
Don’t know answers
Assign middle value
proportions

16. Index Validation
Item analysis (internal validation) – you examine the extent to which the index is related to (or predicts responses to) the individual items it comprises
if the index adequately measures a given variable, it should successfully predict other indications of that variable
External validation – people scored as politically conservative on an index should appear conservative by other measures as well, such as their responses to other items in the questionnaire

17. Scale Construction
Scales offer more assurance of ordinality by tapping the intensity structures among the indicators

18. Bogardus Social Distance Scale
is a measurement technique for determining the willingness of people to participate in social relations – of varying degrees of closeness – with other kinds of people
if a person is willing to accept a given kind of association, he or she would be willing to accept all those preceding it in the list – those with lesser intensities
more people agree to the easy items than to the hard ones
logic demands that once a person has refused a relationship presented in the scale, he or she will also refuse all the harder ones that follow it

19. Thurstone Scales
an attempt to develop a format for generating groups of indicators of a variable that have at least an empirical structure among them
each judge is asked to estimate how strong an indicator of a variable each item is by assigning scores of perhaps 1-13
once the judges have completed this task, the researcher examines the scores assigned to each item by all the judges to determine which items produced the greatest agreement among the judges

20. Likert Scale
- contains responses strongly agree, agree, disagree, and strongly disagree

21. Semantic Differential
asks questionnaire respondents to choose between two opposite positions using qualifiers to bridge the gap between the two opposites
you need to find two opposite terms, representing the polar extremes along each dimensions

22. Semantic Differential Example
Feelings about musical selections:
_____________________________________________________________________
Very much somewhat neither somewhat very much
simple complex
enjoyable unenjoyable
traditional modern

23. Guttman Scale
based on the fact that some items under consideration may prove to be more extreme indicators of the variable than others
begin by examining the face validity of items available for analysis – then you would examine the bivariate and perhaps multivariate relations among those items
also look at hard and easy indicators of the variable being examined
based on the notion that anyone who gives a strong indicator of some variable will also give the weaker indicators

24. Typology
Summarize the intersection of two or more concepts or variables, creating a category or type – nominal variable