An experiment was done to measure the effects of ozone, a component of smog. A group of...

An experiment was done to measure the effects of ozone, a component of smog. A group of 22 seventy-day-old rats were kept in an environment containing ozone for 7 days, and their weight gains were recorded. Another group of 23 rats of a similar age were kept in an ozone-free environment for a similar time, and their weight gains were recorded. The data (in grams) are given below. Analyze the data to determine the effect of ozone. Write a summary of your conclusions. [This problem is from Doksum and Sievers (1976) who provide an interesting analysis.]