Why create a composite of items?

Why create a composite of items?

The rule of thumb in statistics is "the more, the better". In terms of measuring constructs, this means that you typically want to ask many questions about the same construct in order to adequately tap into the entire construct of interest. - in a study about happiness, asking, "how happy are you right now" perfectly maps onto the construct of "how happy you are right now". But, if your intended construct is "happiness", you need to ask more questions to tap the entire theoretical construct, such as asking "how happy do you feel", "how happy are you with your life in general", "how would you rate your happiness level today", how would you rate your happiness level this week", etc.

Thus, for every construct, researchers ask many questions by either using established scales of the topic, or creating their own measures to tap all the facets of the construct. When you analyze the data, you start by conducting descriptive analysis of each individual question. Then, you composite all the questions together into 1 variable by averaging together all the questions. Researchers are typically more interested in that 1 composite variable than the individual items (unless the individual questions are uniquely taping different sub-parts of the entire construct, and the researchers are interested in each sub-part). So, after first conducting descriptive analysis of each item, you then conduct descriptive analysis of the 1 composite variable.