Pose a Question

• Which grocery stores sell cheaper milk?

• Major chain stores or neighborhood stores?

Population of interest:

Major and neighborhood grocery stores

Purpose• We will be conducting a two

sample T test to compare the prices grocery store items at major and neighborhood stores.

• We will be comparing the prices of:

• Dean’s Milk

• We choose to do this project because many people frequent the grocery stores and people would like to know which type of stores sell the cheapest grocery

Conducting an experiment

• We will visit 3 neighborhood stores:

• The Village• Skip’s• Bronzeville Food &Liquors • We will record the price of Dean’s milk

We will also visit 3 major grocery stores:

• Jewel Osco• Wal-mart• Dominick’s• We will also record these prices of

Dean’s milk

• Strengths:• We are directly getting the prices

from each store

• We are using a world wide used grocery item, milk, and getting the same brand of Dean’s Milk

• Weakness:• We are only testing three local &

major grocery stores, so it may not convey accurate store prices for major and local grocery stores

Our Confidence

• We are confident that our sample represents the population because we went to three different areas of Chicago and three of the most popular grocery stores in the United States.

Data

• Neighborhood Grocery Stores :

• Village:– $3.29

• Skip’s:– $4.99

• Bronzeville food & liquors:– $.99

Average milk price:$3.09

• Major Grocery Stores:

• Wal-mart:– $2.99

• Dominick’s:– $3.99

• Jewel Osco:– $3.99

Average milk price:$3.66

Data Summary

• Neighborhood Grocery Stores– Standard Deviation= 2.01– Five Number Summary

• Min= .99• Q1= .99• Med= 3.29• Q3= 4.99• Max= 4.99

• Major Grocery Stores– Standard Deviation= .58– Five Number Summary

• Min= 2.99• Q1= 2.99• Med= 3.99• Q3= 3.99• Max= 3.99

Graph- Histogram

Descriptions of Statistics and Graphs

• Neighborhood Grocery Stores– Shape

• Skewed to the right

– Outliers• Bronzeville Food &

Liquor ($.99)

• Major Grocery Stores– Shape

• Slightly skewed to the left

– Outliers• None

Inference Procedureer

• Ho- Price of milk at neighborhood and major stores are the same.

• Ha- Price of milk at neighborhood and major stores are not the same.

Sample

• We will use the two sample T test

• To determine if local or major grocery stores sell cheaper milk

• Parameters:• Our sample data is

independent

• =[t = [ (x1 - x2) - d ] / SE

Results

• Using the TI-83 Calculator we found that the:

• Df=2• t=.46• SE=1.20• P value=.68

We will reject the alternate hypothesis that Neighborhood stores sell cheaper milk than major grocery stores at the .05 alpha level because our P value is significantly higher.

Conclusion

• We conclude that although neighborhood grocery stores seem as though they would have cheaper milk, and items in general they do not have considerably cheaper prices than major grocery stores.