The Florida Department of Corrections publishes an online death row fact sheet. It reports the average time on death row prior to execution as 11.72 years but provides no standard deviation. This mean is a parameter because it is calculated from the entire population of executed prisoners in Florida. Did the time spent on death row change over time? According to the execution list linked to the same Web site, the six prisoners executed in Florida during the years 2003, 2004, and 2005 spent 25.62, 13.09, 8.74, 17.63, 2.80, and 4.42 years on death row, respectively. (All were men, although Aileen Wuornos, the serial killer portrayed by Charlize Theron in the 2003 film Monster, was among the three prisoners executed by the state of Florida in 2002; Wuornos spent 10.69 years on death row.)

a. Using symbolic notation and formulas (where appropriate), determine the appropriate mean and standard error for the distribution of means. Show all steps of your calculations.

b. Using symbolic notation and the formula, calculate the t statistic for time spent on death row for the sample of executed prisoners.

c. The execution list provides data on all prisoners executed since the death penalty was reinstated in Florida in 1976. Included for each prisoner are the name, race, gender, date of birth, date of offense, date sentenced, date arrived on death row, data of execution, number of warrants, and years on death row. State at least one hypothesis, other than year of execution, which could be examined using a t distribution and the comparison mean of 11.72 years on death row. Be specific about your hypothesis (and if you are interested, you can search for the data online).

d. What additional information would you need to calculate a z score for the length of time Aileen Wuornos spent on death row?

e. Write hypotheses to address the question “Did the time spent on death row change over time?”

f. Using these data as “over time” and the mean of 11.72 years as the comparison, answer the question based on the t statistic calculated in part (b), using alpha of 0.05.

g. Calculate the confidence interval for this statistic based on the data presented.

h. What conclusion would you make about your hypotheses based on this confidence interval? What can you say about the size of this confidence interval?

i. Calculate the effect size using Cohen’s d.

j. Evaluate the size of this effect.