How do I create a composite with items labeled in opposite directions?
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How do I create a composite with items labeled in opposite directions?
- If you are going to composite together multiple items, all the items need to be "in the same direction". This means that indicating a higher (or lower) response each scale must correspond conceptually to answering higher (or lower) on the other items you want to composite together.
- Lets say we ask two happiness questions: (1) "How happy are you right now?" on a 1-7 scale, and (2) "How unhappy you are right now?", on a 1-7 scale. Notice that the two questions are about the same construct (so theoretically you can merge them together), and also notice that the total range of the scales for both items are 7 points, BUT that conceptually answering higher (or lower) on one item is NOT the same as answering higher (or lower) on the other item. If we average together these two items, the resulting average will not be interpretable because of the different scale ranges. - If you are happy, and thus answer a "7" on the first question and a "1" on the second question, when you average them together into 1 composite, the result will be "4" which does NOT accurately indicate your current happiness level.
- The solution is to reverse code the items so that all the questions are in the same direction. - We could either reverse code the scale range for the first item, or the second item (but not obviously both items).
- Composites typically contain multiple items, so you typically have to reverse code multiple items. Also, when choosing which set of items to reverse code (e.g., either the items that are in the positive direction, or items that are in the negative direction), you should think ahead to the statistical analyses you want to conduct and how you want output from those statistical analyses (or the relationship between those variables) to be conceptualized. - Imagine a study testing the relationship between happiness and income. If your hypothesis is that more income is correlated with more happiness, then conceptually you want your "happiness" composite to code in the positive direction (so that higher on the scale means more happiness) so that the outcome is easier to interpret. Notice, that if you code the happiness composite in the opposite direction (so that lower means more happiness), you will still get the same conceptual outcome as with the positively coded composite -- that more happiness is correlated with more income -- but the interpretation of the outcome will be more difficult because you will get a negative correlation between the variables (because lower on the happiness scale is more happiness, and more happiness is correlated with higher income). Thus, think ahead to your intended results and code all the items in the appropriate direction.
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