The recommendations of respected wine critics such as Robert M. Parker, Jr. have a substantial effect on the price of wine. Vintages that earn higher ratings command higher prices and spark surges in demand. These data are a sample of ratings of wines selected from an online Web site from the 2000 and 2001 vintages.
(a) Do the ratings meet the conditions needed for a two-sample confidence interval?
(b) Find the 95% confidence interval for the difference in average ratings for these two vintages. Does one of the years look better than the other?
(c) Suggest one or two possible sources of confounding that might distort the confidence interval reported in part (b).
(d) Round the endpoints of the interval as needed for presenting it as part of a message.
(e) Given a choice between a 2000 and 2001 vintage at the same price, which produces higher ratings? Does it matter?