The amount of time single men and women spend on house work is measured for 15 single women and 20 ...

The amount of time single men and women spend on house work is measured for 15 single women and 20 single men. What are the appropriate degrees of freedom for the multiplier t for a pooled confidence interval for the difference in mean time spent on housework between single men and women?
 a. 14
  b. 19
  c. 33
  d. 35

Q. 2

For each study, decide if the two samples are independent samples or paired samples. A study compared the average number of courses taken by a random sample of 100 freshmen at a university with the average number of courses taken by a separate random sample of 50 freshmen at a community college.
 a. Independent samples
  b. Paired samples

Q. 3

Which one of the following ways of collecting data would result in two independent samples?
 a. A sample of college students is measured for stress both before and after taking an important exam.
  b. A group of college students are paired based on gender, age, major, and grades. One student in a pair receives stress management training and the other one does not. After a few weeks all students are measured for stress right before an important exam.
  c. A sample of English majors is measured for stress before taking an important exam. A sample of engineering majors is also measured for stress before taking their important exam.
  d. A sample of college students is measured for stress before taking an important exam. Their exam grade is also recorded.

Q. 4

For each study, decide if the two samples are independent samples or paired samples. A group of 50 students each measured the length of their right arm and the length of their left arm. The average right arm lengths were compared to the average left arm lengths.
 a. Independent samples
  b. Paired samples

Q. 5

When constructing a confidence interval for the difference in two population means, it is appropriate to use the pooled standard error only when
 a. the population standard deviations can be assumed to be equal.
  b. the sample standard deviations are exactly equal.
  c. the population means can be assumed to be equal.
  d. the sample means are exactly equal.

Q. 6

Contradicting some previous research, a new study finds that frequent use of painkillers does not substantially increase a healthy man's risk of developing hypertension. The study finds that the observed difference between the two groups was not statistically significant. Explain in your own words what that means.

Q. 7

Managerial training programs often teach supervisory skills. Are these training programs effective? A company psychologist administers a test to each of 10 supervisors before and after attending such a training program. Higher scores indicate increased supervisory skills. The results are used to estimate the mean improvement in supervisory skills. Does it appear that the training program is effective? Explain how you came to your decision.