The case:

- I have variable of overall satisfaction (measured by 5 point rating scale) withing 20 stores

- The overall satisfaction was measured in 4 quarters of the year 2020

- The task is to calculate average satisfaction (score) of the two best quarters within each store

- And then compare the means and determine the significant difference

How should I do this, more precisely which statistical test (probably t-test) should be used?

Many thanks for help!!