THE STUDY 

 SAMPLING

            The question I wished to answer with this topic is whether more people shop at grocery stores in the afternoon or at night.  First, I had to select the time intervals in which I would conduct my study.  I chose 2:30 p.m. to 3:30 p.m. for the afternoon interval and 8:30 p.m. to 9:30 p.m. for the night interval.  I then had to decide on what days I was going to conduct my study.  I gave every day from the March 24, 2007 to May 10, and I used a random number generator to select 32 numbers in case for some reason I could not conduct my study on one or two days.  I did this for each time interval in order to receive two independent and random samples.  On the determined days, I went up to the store at which I chose to conduct this study, the Rocky River Giant Eagle, and sat there during the time interval, simply counting the number of people entering the store.  The population of interest was all customers of this particular store.  Because one of the days selected for the afternoon sample was the day of the AP Statistics test I was unable to collect data on that day.  My final result was a sample size of 31 for the afternoon time period and a sample size of 32 for the night period.

HYPOTHESIS TEST

 μ₂= True mean number of customers entering a grocery store from 8:30 p.m. to 9:30 p.m.

H_o:  μ₁=μ₂

H_a:  μ₁>μ₂

 α = 0.05

 Assumptions:  Both samples were random and independent.  Both samples sizes are greater than  30 so the central limit theorem applies.

  t =

  T-Value = 18.83

  57 DF

  P-Value = 0.000