Number of Walks for a Baseball Team in a Season. The dataset BaseballHits gives 2010 season statistics for all Major League Baseball (MLB) teams. We treat this as a sample of all MLB teams in all years. Computer output of descriptive statistics for the variable giving the number of Walks is shown below:

Computer Printout of Descriptive Statistics: Walks

Variable	N	N*	Mean	SE Mean	StDev
Walks	30	0	525.9	11.5	63.2

Minimum	Q1	Median	Q3	Maximum
415.0	471.0	524.5	559.3	672.0

• How many teams are included in the dataset? What is the mean number of walks? What is the standard deviation?

• Compute the standard error for the mean using the formula SE = s/n. Compare the result to the value given under SE Mean in the computer output.

• Use the summary statistics to compute a 95% confidence interval for the mean number of walks per team in a season.

• Compare the answer from part (c) to the confidence interval given in the following computer output for the same data:

Computer Printout of One-Sample T: Walks

Variable	N	Mean	StDev	SE Mean	95% CI
Walks	30	525.9	63.2	11.5	(502.3, 549.6)

• ) Interpret the confidence interval in context.

PART 4 (Section 6.9): problem #6.204 (p. 409)

THC vs Prochloroperazine. An article in the New York Times on January 17, 1980 reported on the results of an experiment that compared an existing treatment drug (prochloroperazine) with using THC (the active ingredient in marijuana) for combating nausea in patients undergoing chemotherapy for cancer. Patients being treated in a cancer clinic were divided at random into two groups, which were then assigned to one of the two drugs (so they did a randomized, double-blind, comparative experiment). Table 6.15 shows how many patients in each group found the treatment to be effective or not effective.

• Use these results to test whether the proportion of patients helped by THC is significantly higher (no pun intended) than the proportion helped by prochloroperazine. Use a 1% significance level since we would require very strong evidence to switch to THC in this case. [Fully describe your testing and analysis.]

• Why is it important that these data come from a well-designed experiment?