9.51 Paired-samples t tests, confidence intervals, and hockey goals: Below are the numbers of goals scored by the leading scorers on the New Jersey Devils ice hockey team in the 2007–2008 and 2008–2009 seasons. On average, did the Devils play any differently in 2008–2009 than they did in 2007–2008?

Player 2007–2008 2008–2009 Elias 20 31 Zajac 14 20 Pandolfo 12 5 Langenbrunner 13 29 Gionta 22 20 Parise 32 45

a. Conduct the six steps of hypothesis testing using a twotailed test and an alpha level of 0.05.

b. Report the test statistic in APA format.

c. Calculate the confidence interval for the paired-samples t test you conducted in part (a). Compare the confidence interval to the results of the hypothesis test.

d. Calculate the effect size for the mean difference between the 2007–2008 and 2008–2009 seasons.