5 points Chapters 9 & 10. Please answer the following questions on a separate piece of paper. 1. (a) In general, what does the null hypothesis always predict? (b) If the statistical analysis allows the researcher to reject the null hypothesis, does this prove that the null hypothesis is false? Explain your answer. 2. What is meant by practical significance? Explain your answer. 3. Explain how to find t.05 (known as the critical value of t for p = .05) for: the one-sample t-test and the matched-pairs t-test. 4. An experimenter interested in the causes of headaches suspects that much of the discomfort people suffer is from muscle tension. She believes that if people could relax the muscles in the head and neck region, the pain of a headache would decrease. Nine subjects are randomly selected from a headache pain clinic and asked to keep track of the number of headaches experienced over a two week period (baseline measurement). The subjects then completed a 6-week seminar in biofeedback training to learn how to relax the muscles in their head and neck. After completing the seminar, the subjects were then asked to record the number of headaches they experienced over a two week period using their new biofeedback skills. The number of headaches reported by subjects before and after the biofeedback training seminar are reported below. Subject #: 1 2 3 4 5 6 7 8 9 Before Seminar: 17 13 6 5 5 10 8 6 7 After Seminar: 3 7 2 3 6 2 1 0 2 a. Describe (1) the independent variable and its levels, and (2) the dependent variable and its scale of measurement. b. Describe the null and alternative hypotheses for the study described. c. Using Excel, conduct a statistical test of the null hypothesis at p = .05. Be sure to properly state your statistical conclusion. d. Provide an interpretation of your statistical conclusion in part C. e. What type of statistical error might you have made in part C?5. An educator wants to determine if early exposure to school will affect IQ. He enlists the aid of the parents of 10 pairs of preschool-age identical twins who agree to let their twins participate in his experiment. One member of each twin pair is enrolled in preschool for 2 years, while the other member of each pair remains at home. At the end of 2 years, subjects in both conditions were given an intelligence test. The test scores recorded are given below. Pair #: 1 2 3 4 5 6 7 8 9 10 Preschool: 110 121 107 117 119 125 130 116 118 110 Home: 95 105 109 120 104 100 128 110 100 93 a. Describe (1) the independent variable and its levels, and (2) the dependent variable and its scale of measurement. b. Describe the null and alternative hypotheses for the study described. c. Using Excel, conduct a statistical test of the null hypothesis at p = .05. Be sure to properly state your statistical conclusion. d. Provide an interpretation of your statistical conclusion in part C. 6. Based on previous research and sound theoretical considerations, an experimental psychologist believes that memory for pictures is superior to memory for words. To test this hypothesis, the psychologist performs an experiment in which students from a introductory psychology class are used as subjects. Eight randomly selected students view 30 slides with nouns printed on them, and another group of eight randomly selected students view 30 slides with actual pictures of the same nouns. Each slide contains either one noun or one picture and is viewed for 4 seconds. After viewing the slides, students are given a recall test. The number of correctly recalled items is recorded. The data collected are given below. # of pictures recalled: 18 21 14 25 23 19 26 15 # of nouns recalled: 12 9 21 17 16 10 19 22 a. Describe (1) the independent variable and its levels, and (2) the dependent variable and its scale of measurement. b. Describe the null and alternative hypotheses for the study described. c. Using Excel, conduct a statistical test of the null hypothesis at p = .05. Be sure to properly state your statistical conclusion. d. Provide an interpretation of your statistical conclusion in part C. e. Construct the 95% confidence interval using the obtained sample statistic. f. Provide an interpretation of the interval obtained in part E.7. A psychologist is interested in determining whether immediate memory capacity is affected by sleep loss. Immediate memory is defined as the amount of material that can be remembered immediately after it has been presented. Twelve students are randomly selected from lower division college courses and randomly assigned to two groups of 6 each. One of the groups is sleep deprived for 24 hours before the material is presented. All subjects in the other group receive the normal amount of sleep (7-8 hours). The material consists of a series of slides, with each slide containing nine numbers. Each slide is presented for a short time interval (50 milliseconds), after which the subject must recall as many numbers as possible. On the following page are the results. The scores represent the percentage correctly recalled. Normal Sleep Group: 68 73 72 65 70 73 Sleep Deprived Group: 70 62 68 63 69 60 a. Describe (1) the independent variable and its levels, and (2) the dependent variable and its scale of measurement. b. Describe the null and alternative hypotheses for the study described. c. Using Excel, conduct a statistical test of the null hypothesis at p = .05. Be sure to properly state your statistical conclusion. d. Provide an interpretation of your statistical conclusion in part C. Chapter 10 8. Describe when it is appropriate to use (A) one-way or single factor chi-square test, and ( B) two-way or two-factor chi-square test. 9. Generally speaking, what scale of measurement are the data analyzed by the chi-square test? 10. A designer of electronic equipment wants to develop a calculator which will have market appeal to high school students. Past marketing surveys have shown that the color of the numeric display is important in terms of market preference. The designer makes up 210 sample calculators and then has random sample of students from the area high schools rate which calculator they prefer. The calculators are identical except for the color of the display. The results of the survey were that 96 students preferred red, 82 preferred blue, and 32 preferred green. a. Describe (1) the independent variable and its levels, and (2) the dependent