* SHOW ALL WORK - AND DO EACH STEP OF THE HYPOTHESIS TEST SUMMARY * MUST HAVE A t-score (or z-score), EVEN IF YOU GIVE ME A P-VALUE (other than the literally last Two, 1 point questions on the exam)
STATISTICS FOR THE BEHAVIORAL SCIENCES
PSYN/SOCL/BHSC 370 DLB
Instructor: David Geber
CHAP 10, 13-15 FINAL NAME ________
CHAPTER 10 HYPOTHESIS TEST SUMMARY (SHOW ALL WORK) The z-Test
According to a 2009 U.S. Census Bureau survey during, the daily one-way commute time of U.S. workers averages 25 minutes with , we'll assume, a standard deviation of 14 minutes. An investigator wishes to determine whether the national average describes the commuter time for all workers in the Chicago area. Commute times are obtained for a random sample of 144 workers from this area, and the mean time is found to be 28.5 minutes. Test the Null Hypothesis at the .05 level of significance
CHAPTER 13 HYPOTHESIS TEST SUMMARY – ONE SAMPLE t Test (Show all work)
Assume that on average, healthy young adults dream 90 minutes each night, as inferred from a number of measures, including rapid eye movement (REM) sleep. An investigator wishes to determine whether drinking coffee just before going to sleep affects the amount of dream time. After drinking a standard amount of coffee, dream time is monitored for each of 28 healthy young adults in a random sample. Results show a sample mean (X-bar), of 88 minutes and a sample standard deviation, s, of 9 minutes. Test the Null Hypothesis with t, using the .05 level of significance and construct a 95 percent confidence interval (whether you reject OR retain the null hypothesis)
CHAPTER 13 HYPOTHESIS TEST SUMMARY – ONE SAMPLE t Test (Show all work)
A professor wants to know if her introductory statistics class has a good grasp of basic math. Six students are chosen at random from the class and given a math proficiency test. The professor wants the class to be able to score above 80 on the test. The six students get scores of 72, 92, 85, 68, 83, and 95. Test the Null Hypothesis with t, using the .01 level of significance and construct a 99 percent confidence interval (whether you reject OR retain the Null Hypothesis
CHAPTER 14 HYPOTHESIS TEST SUMMARY – t Test for TWO INDEPENDENT SAMPLES (Show all Work)
To determine whether training in a series of workshops on creative thinking increases IQ scores, a total of 80 students are randomly divided into treatment and control groups of 40 each. After two months of training, the sample mean IQ (X-bar1) for the treatment group equals 110 , and the sample mean IQ (X-bar2) for the control group equals 108. The estimated standard error equals 1.80. Test the Null Hypothesis with t, using the .05 level of significance and construct a 95 percent confidence interval (whether you reject OR retain the Null Hypothesis)
CHAPTER 14 HYPOTHESIS TEST SUMMARY – t Test for TWO INDEPENDENT SAMPLES (Show all work)
Does right‐ or left‐handedness affect how fast people type? Random samples of students from a typing class are given a typing speed test (words per minute), and the results are compared (see below). Test the Null Hypothesis with t, using the .01 level of significance and construct a 99 percent confidence interval (whether you reject OR retain the Null Hypothesis)
Group 1…...Right Handed…….n = 12…..Sample Mean = 55.8…..SS = 358
Group 2…….Left Handed…….n = 12…..Sample Mean = 59.3…..SS = 203
CHAPTER 15 HYPOTHESIS TEST SUMMARY – t Test for TWO DEPENDENT (Related) SAMPLES (show all work)
7) A manufacturer of a gas additive claims that it improves gas mileage. A random sample of 20 drivers tests this claim by determining their gas mileage for a full tank of gas that contains the additive (X1) and for a full tank of gas that does not contain the additive (X2). The sample mean difference D-Bar equals 3.12 miles (in favor of the additive) and the estimated standard error equals 1.50 miles. Test the Null Hypothesis with t at the .05 level of significance and construct a 95 percent confidence interval (Whether you retain OR reject the Null Hypothesis)
CHAPTER 15 HYPOTHESIS TEST SUMMARY – t Test for TWO DEPENDENT SAMPLES (show all work)
A farmer out a new fertilizer on decides to try a test plot containing 10 stalks of corn. Before applying the fertilizer, he measures the height of each stalk. Two weeks later, he measures the stalks again, being careful to match each stalk's new height to its previous one. The stalks would have grown an average of 6 inches during that time even without the fertilizer. Did the fertilizer help? Test the Null Hypothesis with t, using the .05 level of significance and construct a 95 percent confidence interval (whether you reject OR retain the Null Hypothesis)
hypothesis null: H 0: μ = 6
alternative hypothesis: H a : μ > 6
Find the critical t-values for the following hypothesis tests: (1 pt each)
(a) two-tailed test, level of Significance = .01, df = 8 _____________
(b) one-tailed test, lower tail critical, level of significance = .05, df = 24 ____________
(c) one-tailed test, upper tail critical, level of significance = .01, df = 17 ______________
(d) two-tailed test, level of Significance = .05, df = 25 ____________
(e) two-tailed test; level of significance .01, n1 = 8 n2 = 6 ___________
(f) one-tailed test, lower tail critical; level of significance .05, n1 = 14, n2 = 11 _________
(g) one-tailed test, upper tail critical; level of significance .01, n1 = n2 = 12 ____________
(h) two-tailed test; level of significance .05, n1 = 9, n2 = 13 __________________
Find the approximate p-value for each of the following test results: (1 pts each)
(a) one-tailed test, lower tail critical: df = 12, t= -2.92 __________
(b) two-tailed test: df = 28, t = 3.622 ____________
