What is the definition of a Research Variable? Below is the example he gave, but never actually told us what the definition is.

Here is an example:

I have an issue with the lack of customers coming into my store. I would choose the research variable daily customers to collect data on.

Through my customer photocell system, I will be able to know the daily number of customer and compile this information in a list for later analysis.

My problem is aligned with my research variable which is aligned with my data collection. Each of the components make sense in relation to the others.