I am working on a case study in a nutshell what I a looking at happens at a family gathering. One gentleman is a manager of a small grocery store he speaks with his cousin who supervises a large number of data-entry workers at a public utility company. The cousin share that they are playing background music in the data-entry room, productivity has increased and errors decreased. The grocery store manager thinks this might impact his shoppers to stay the store longer if it was easy listening slow music. The grocery store manager decided to hire a marketing research manager to design an experiment to test the influence of the music tempo on shopper behavior.

I am just having a terrible time with isolation of independent variable(s) versus dependent variable(s) in this scenario.