Please define a summation index and give a detailed example of how you would use a summation scale to create a variable of your choice.

Question

What will be an ideal response?

Answer 1

The answer will vary by the example chosen by the student but should otherwise be similar to the answer below. A summation index is a method of accumulating scores on individual items to form a composite measure of a complex phenomenon. An index is constructed by assigning a range of possible scores for a certain number of items, determining the score for each item for each observation, and then combining the scores for each observation across all the items. The resulting summary score is the representative measurement of the phenomenon. Attitudes are complex phenomena, and we usually do not know enough about them to devise single-item measures. So we often ask several questions of people about a single attitude and aggregate the answers to represent the attitude. A researcher might measure attitudes toward abortion, for example, by asking respondents to choose one of five possible responses—strongly agree, agree, undecided, disagree, and strongly disagree—to the following three statements: (1) Abortions should be permitted in the first three months of pregnancy; (2) Abortions should be permitted if the woman’s life is in danger; (3) Abortions should be permitted whenever a woman wants one. An index of attitudes toward abortion could be computed by assigning numerical values to each response (such as 1 for strongly agree, 2 for agree, 3 for undecided, and so on) and then adding the values of a respondent’s answers to these three questions. (The researcher would have to decide what to do when a respondent did not answer one or more of the questions.) The lowest possible score would be a 3, indicating the most extreme pro-abortion attitude, and the highest possible score would be a 15, indicating the most extreme anti-abortion attitude. Scores in between would indicate varying degrees of approval of abortion.