Wednesday April 9, 2014

**Copycat Bank Robbers**

Police departments aren't very happy when a successful bank heist is reported in the media.

They obviously fear that
so-called copycat bank robbers will be inspired and emboldened by the success of the reported robbery. To determine if a copycat
effect exists, a study by the Australian Centre for Policing Research looked at the number of bank robberies in the 7 days before and

the 7 days after a successful bank robbery that was covered in the media. If the mean number of bank robberies is higher in the 7 days
after the successful bank robbery, then this may be evidence of a copycat effect. Bring up the data set copycat_robberies.mtw, which

presents data that is consistent with summary quantities given in the report. The data are comprised of the number of robberies before
and after 49 successful bank robberies covered by the media.

Test the data for the presence of a copycat effect using significance level alpha=0.05 --- state hypotheses, report test
statistic and p-value, and give your conclusions.

Memory Recall Study

In a study of memory recall, 8 students from a large psychology class
were selected at random and

given 10 minutes to memorize a list of 20 unrelated words. Each
student was asked to list as many

words as he or she could
remember both 1 hour and 24 hours after. The data are found in
the Minitab worksheet memory_recall_1_24.mtw.

(a) Is there evidence of a "forgetfulness effect"? In other
words, is there a significant loss of the

number of memorized words, on average, from 1 to 24 hours? Use
significance level alpha=0.01.

(b) Is there evidence that the number of words recalled after 1
hour exceeds the number recalled

after 24 hours by more than 3 words, on average? Again, use alpha=0.01.

(c) Find a 99% confidence interval for the mean number of words
"forgotten" between 1 and 24

hours after reading the word list.