Comparing Grocery Prices at Trader Joe's and Safeway. A consumer group suspects that there is a difference in prices between Trader Joe's and Safeway. Specifically, they want to test the claim that Trader Joe's is less expensive than shopping at Safeway. To investigate this, they identified the prices of several items at both stores. Since prices change over time, all the data was gathered on a single day. At the 5% level of significance, is there enough evidence to conclude that shopping at Trader Joe's is less expensive than shopping at Safeway? Consider Trader Joe prices to be from population 1, and Safeway prices to be from population 2. Assume the population of price differences is normally distributed. This is not an unreasonable assumption as often prices are normally distributed. Also assume that the data represents a SRS(simple random sample) of items at the two stores. A note on the data: Students in a prior class collected this data. I have excluded all alcohol and plant items, as the prices on these items is heavily in favor of one of the stores. The data can be located in the module 9 block of our reading and assignments, and also here : LINK 1) Why is this a matched pairs test?