250 STAT Spring 2009 Quiz 10 Please write your name on your scantron form. Mark your answers on this question paper and scantron form. When you have finished the quiz, please put your scantron inside the Quiz and wait until your professor asks you to return it. Multiple Choice. Choose the one alternative that best completes the statement or answers the question. 1. Classify the two given samples as independent or dependent: Sample 1: Pre-training weights of 28 people Sample 2: Post-training weights of the same 28 people a. dependent b. interdependent c. independent d. not mutually exclusive
2. If the individual selected for a sample have no influence upon which individuals are selected for a second sample, then the samples are said to be______. a. dependent b. interdependent c. independent d. not mutually exclusive
X is the stress rating before a person learns a new relaxation technique and Y is the stress rating after that same person learns and uses this new relaxation technique. The researcher is testing if the technique will reduce stress. Assuming the data comes from a population that is normally distributed and that X and Y are dependent, calculate the test statistic when n = 10, d = 1.18 and sd = 0.89. Use this information to answer questions 3 and 4:
3. Calculate the test statistic, t0. a. 1.67 b. 4.19 c. -1.67 d. -4.19
4. Construct the 95% confidence interval for the difference of these two means in this matched pairs case. a. 1.18 b. 1.18 0.697 0.637 c. 1.18 d. 1.18 0.574 0.567
5. We are testing whether the mean of population A is larger than the mean of population B. If d= A B, then the alternative hypothesis should read: a. H1: d > 0 b. H1: d 0 c. H1: d < 0 d. H1: d 0
A sample of 22 teachers from district A had a mean salary of $28, 500 and a standard deviation of $2500. A sample of 22 teachers from district B had a mean salary of $30,500 with a standard of deviation $2000. Assume that the populations are normally distributed and independent.
2 s12 s2 + = 682.6 for this problem. Use this information for questions 6 n1 n2
The standard error, and 7.
6.
Construct a 90% confidence interval for B A. a. (597, 4081) b. (238, 2054) c. (567, 2871) d. (825, 3175)
7. Test the claim that the mean salary of teachers from district B is different than the mean salary of teachers from district A at a 0.01 significance level given the test statistic is 2.930. (That is test H0: B= A against H1: B A at a 0.01 significance level given the test statistic is 2.930.) a. At a 0.01 significance level, there is sufficient evidence to support the claim that the mean salary of teachers from district B is different than the mean salary of teachers from district A. b. At a 0.01 significance level, there is insufficient evidence to support the claim that the mean salary of teachers from district B is different than the mean salary of teachers from district A.
A researcher is interested in determining whether or not the proportion of incoming female students who major in IT has increased. A sample of female students taken several years ago is compared with a sample of female students taken this year. Results are summarized below: Sample Size Number if IT Female Students Sample from several years ago (Sample 1) 500 180
Sample from this year (Sample 2)
600
200
^ ^ (So p1 = 0.36 and p2 = 0.33 ). Use the above information to answer questions 8-10.
8. Calculate the point estimate of the difference (p1 p2).
a. 0.03 b. 0.5
c. -0.04 d. -20
^ 9. The pooled proportion ( p ) has a value of:
a. 0.34 b. 0.35
c. 0.5 d. 3.41
10. Test the claim that the proportion has decreased from several years ago. At an = 0.05 (significance level of 0.05) and a p-value = 0.177, your conclusion is:
a. Do Not Reject H0 b. Reject H0
c. Accept H0 d. None of the above.