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:

(a) How many teams are included in the dataset? What is the mean number of walks? What is the standard deviation?
(b) Compute the standard error for the mean using the formula SE = s/ˆšn. Compare the result to the value given under €˜€˜SE Mean€ in the computer output.
(c) Use the summary statistics to compute a 95% confidence interval for the mean number of walks per team in a season.
(d) Compare the answer from part (c) to the confidence interval given in the following computer output for the same data:

(e) Interpret the confidence interval in context.

Transcribed Image Text:

Descriptive Statistics: Walks Variable Walks SE Mean StDev N N* Mean 525.9 30 0 11.5 63.2 Q3 Maximum Minimum Q1 Median 415.0 471.0 524.5 559.3 672.0 One-Sample T: Walks Variable Walks N Mean StDev 95% CI 525.9 63.2 SE Mean 11.5 (502.3, 549.6) 30