Validating scales and indexes
Here's an example of what they look like: Your reading intentions are also stored in your profile for future reference.Quantitative data analysis requires the construction of two types of measures of variables--indices and scales.Another important indicator of an index’s validity is how well it accurately predicts related measures.For example, if you are measuring political conservatism, those who score the most conservative in your index should also score conservative in other questions included in the survey.The final step in constructing an index is validating it.Just like you need to validate each item that goes into the index, you also need to validate the index itself to make sure that it measures what it is intended to measure. One is called in which you examine the extent to which the index is related to the individual items that are included in it.An index is composite measure of variables, or a way of measuring a construct--like religiosity or racism--using more than one data item.
First, you should select items that have face validity.
Secondly, researchers seek to establish ordinal categories from very low to very high (vice-versa), which single data items can not ensure, while an index or scale can.