Question

Explain and describe the steps in index construction.

Answer 1

An index is collection of scores from different individual items. To construct an index, we have to select possible items, examine their empirical relationships, score the index, and then finally validate it.

The first step in creating an index is selecting the items you wish to include in the index to measure the variable of interest. There are several things to consider when selecting the items. First thing is you should select items that have face validity that means the item should measure what it is intended to measure. If you are constructing an index of religiosity, items such as church can be selected. A second criterion for choosing which items to include in your index is unidimensionality. That is, each item should represent only one dimension of the concept you are measuring. For example, items reflecting depression should not be included in items measuring anxiety.

The second step in index construction is to examine the empirical relationships among the items you wish to include in the index. An empirical relationship is when respondents answers to one question help us predict how they will answer other questions. If two items are empirically related to each other, we can argue that both items reflect the same concept and we can therefore include them in the same index.

The third step in index construction is scoring the index. You assign scores for particular responses, thereby making a composite variable out of your several items. The final step in constructing an index is validating it.