Psychology 60 Fall 2013 Practice Exam Actual Exam: Next Monday. Good luck!

Psychology 60 Fall 2013 Practice Exam Actual Exam: Next Monday. Good luck! Name: 1. The basic idea behind hypothesis testing: A. is important only if you want to compare two populations. B. depends on the kind of test you want to run. C. is largely the same across a wide variety of procedures D. has little to do with whatever data you collect. 2. If data are reasonably consistent with the null hypothesis, we are likely to: A. fail to reject the null hypothesis B. reject the null hypothesis C. accept the null hypothesis D. accept the alternative hypothesis E. both a and c. 3. We are most likely to reject a null hypothesis if the test statistic we compute is: A. very small. B. equal to the number of observations in the sample. C. quite extreme. D. what we would expect if the null hypothesis were true. 4. A population has µ = 80 and σ = 8. The distribution of sample means for samples of size n = 4 selected from this population would have a standard error of: A. 2 B. 8 C. 4 D. 80 E. None of the above. 5. A sample of n = 16 scores is obtained from a population with µ = 70 and σ = 20. If the sample mean is M = 75, then the Z-score corresponding to the sample mean is: A. Z =.50 B. Z = 2.00 C. Z = 1.00

D. Z = 0.25 6. Which of the following pairings is correct? A. Type I; Type II :: α; β B. Type I; Type II :: α; 1 β C. Type I; Type II :: β; α D. Type I; Type II :: 1 α;1 β 7. Choose the best answer. If we erroneously conclude that motorists are more likely to honk at low status cars than high status cars, we: A. have made a Type II error. B. have made a Type I error. C. have made a Type I error, and would have made that conclusion 5 percent of the time if the null hypothesis were true. D. would have made that conclusion 5 percent of the time if the null hypothesis were true. E. Both A and B. 8. A researcher was interested in seeing if males or females in large lecture classes fell asleep more during in-class videos. The null hypothesis of this study is: A. males will fall asleep more than females B. females will fall asleep more than males. C. males and females fall asleep at the same rate. D. More information is needed. 9. Professor Lowe expected that her graduate student TAs would come significantly earlier to all scheduled appointments compared to her undergraduate TAs, and planned to run a one-tailed test to see if their arrival times were much earlier. Unfortunately, she found the opposite result: the graduate TAs came to appointments later than the undergraduate TAs. What can Professor Lowe conclude from her one-tailed test? A. Graduate student TAs came to appointments significantly later than undergrad TAs. B. Undergrad TAs came to appointments significantly earlier than graduate TAs. C. Graduate TAs did not come to appointments significantly earlier than undergraduate TAs. D. Graduate TAs came to appointments significantly earlier than undergraduate TAs. 10. A random sample of n = 4 scores is obtained from a normal population with µ = 20 and σ = 4. What is the probability of obtaining a mean greater than M = 22 for this sample?

A. 1 B..3085 C..1587 D..50 E. Cannot determine from information given. 11. Which of the following is a major difference between a hypothesis test with the t statistic formula and the test with a Z-score? A. You must know the population variance (or standard deviation) for the z-score but not for the t-statistic. B. You must use the unit normal table to find critical values for the z-score test but not for the t-test. C. You must calculate the sample variance (or standard deviation) for the t- statistic but not for the z-score. D. All of the above are major differences between a hypothesis test with the t- statistic formula and the test with a z-score. 12. With α =.01, what is the critical t value for a one-tailed, one-sample t-test with n = 30? A. t = 2.457 B. t = 2.750 C. t = 2.462 D. t = 2.756 13. A research study uses a single sample of participants to evaluate the effect of a treatment. The results of the hypothesis test are reported as follows: t(14) = 2.73, p <.05 Based on this report, how many individuals were in the sample? A. Cannot determine from the information given. B. 14 C. 15 D. 13 E. 2.73 14. Choose the best answer. Using the same report from the previous question, were the researchers able to reject the null hypothesis at α =.05? A. Cannot determine from the information given. B. Yes. C. No.

D. Yes, BUT the variance of 14 means we cannot trust the results of this hypothesis test. E. No, BUT the variance of 14 means our sample was underpowered. 15. As sample variance increases, what happens to Cohen s d? A. Nothing. Sample variance does not affect cohen s d. B. It tends to decrease. C. It tends to increase. D. The effect of the sample variance depends on the sample size. 16. The null hypothesis for the independent-measures t-test states: A. µ 1 µ 2 = 0 B. M 1 M 2 = 0 C. M 1 M 2 0 D. µ 1 µ 2 0 17. A researcher reports the results of an independent samples t-test: t(24) = 5.30 How many individuals participated in the entire experiment? A. 24 B. 23 C. 25 D. 26 18. Mean scores in Tetris were recorded for both math majors and English majors. The mean score for math majors was 20,752 (s 2 1 = 851, N 1 = 17) and the mean score for English majors was 14,922 (s 2 2 = 395, N 2 = 56). The pooled variance would probably be closest to which value? A. 800 B. 500 C. 900 D. 623 19. If sample size n is held constant, the standard error will??? as the population variance increases. A. stay constant B. decrease C. increase

D. Cannot answer with information given. 20. A sample is obtained from a population with µ = 50 and σ = 8. Which of the following samples would produce the most extreme z-score? A. A sample of n = 4 scores with M = 54. B. A sample of n = 16 scores with M = 52. C. A sample of n = 16 scores with M = 54. D. A sample of n = 4 scores with M = 52. 21. Which of the following research situations is most likely to use an independent-measures design? A. Evaluate the development of verbal skills between age 2 and age 3 for a sample of girls. B. Evaluate the effectiveness of a cholesterol medication by comparing cholesterol levels before and after the medication. C. Evaluate the effectiveness of a diet program by measuring how much weight is lost during 4 weeks of dieting. D. Evaluate the difference in verbal skills between 3-year-old girls and 3-year-old boys. 22. What is the power in an experiment with two independent groups when the null hypothesis is true? A..05 B. undefined C..95 D..05/2 23. One sample of n = 5 scores has a variance of s 2 = 10 and a second sample of n = 10 scores has s 2 = 20. If the pooled variance is computed for these two samples, then the value obtained will be? A. closer to 20 than to 10 B. exactly half way between 10 and 20 C. closer to 10 than to 20 D. cannot be determined without more information. 24. For an independent-measures research study, the value of Cohen s d or r 2 helps to describe: A. whether the difference between the two treatments is likely to have occurred by chance. B. how much difference there is between the two treatments.

C. the risk of a Type I error. D. the risk of a Type II error. 25. Suppose that we know that the sample mean is 18 and the population standard deviation is 3. We want to test the null hypothesis that the population mean is 20. In this situation we would: A. reject the null hypothesis at α =.01 B. reject the null hypothesis at α =.05 C. retain the null hypothesis. D. We cannot solve this problem without knowing the sample size. 26. Which of the following statistics comparing a sample mean to a population mean is most likely to be significant if you used a two-tailed test? A. t = 0.9 B. t = 10.6 C. t = 10.6 D. both t = 10.6 and t = 10.6 27. Use the following situation to answer questions 26-28. To evaluate the effect of a treatment, a sample of n = 9 is obtained from a population with a mean of µ = 40, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be 33, with a sample variance of 81. Calculate and report the value of the appropriate test statistic used to determine if there is evidence of an effect of treatment. A. 2.33 B. -2.33 C. -.78 D. +.78 E. Unable to determine from the information provided. 28. In the above example, what is the critical t value for a two-tailed test with α =.05? A. 1.860 B. -1.860 C. 2.306 D. -2.306 E. None of these. 29. Using the same information as in question 27, suppose you had reason to expect that the treatment would raise individuals mean score, so you conduct a one-tailed test with α =.01. What would be your critical t value?

A. -2.896 B. +2.896 C. +3.355 D. -3.355 E. None of these. 30. To look at the sampling distribution of the mean we would: A. calculate many means and plot them. B. look the sampling distribution up in a book. C. calculate a mean and compare it to the standard deviation. D. calculate a mean and compare it to the standard error. 31. Which combination of factors produces the smallest risk of a Type I error if the null hypothesis is actually true? A. α =.05, n = 30, σ = 10 B. α =.05, n = 100, σ = 10 C. α =.05, n = 30, σ = 20 D. α =.05, n = 10, σ = 5 E. All of the above have the same Type I error risk if the null hypothesis is true. 32. Which of the following is sometimes a serious problem with repeated measures designs? A. They require more subjects than designs with independent samples. B. All of these choices. C. Small sample sizes can distort the results more than with other designs. D. Carryover effects can cloud the interpretation. 33. As they were running their statistical analyses on the computer, Blaze accidentally changed the α level from.05 to.50. With this change, what happened to the risk of a Type I error? A. It decreased. B. It increased. C. It stayed the same. The risk of type I error is not affected by the alpha level. D. Unable to determine from the information given. 34. A researcher is investigating the effect of a new food on empathy scores and is using a two-tailed hypothesis test. What happens if this researcher increases the value of alpha from.05 to.20? A. The probability of rejecting H 1 increases, if H 0 is true.

B. The probability of rejecting H 0 increases, if H 1 is true. C. The probability of rejecting H 0 increases, if H 0 is true. D. Both B. and C. E. None of these. 35. Imagine you draw a sample of 100 samples from a population with a mean of 57 and a standard deviation of 20. What are the mean and the standard error for the sampling distribution? A. mean = 57, s.e. = 20 B. mean = 60, s.e. = 12 C. mean = 60, s.e. = 2 D. mean = 57, s.e. = 2 36. As the value of the mean difference score decreases: A. the t score stays the same. B. the t score decreases. C. the t score increases. D. We cannot determine from information given. 37. Imagine that you select a sample of N = 25 women from Ourtown and find that the mean height of the sample is 5 feet, 7 inches (67 inches). The population mean is known to be 5 feet, 4 inches (64 inches) with SD = 3 inches. Would a sample mean this large be more likely or less likely if N = 5? Why? A. Equally likely. Sample means are randomly distributed. B. More likely. The sampling distribution of the mean would be wider if the sample were smaller, so sample means would be more likely to be farther from the population mean. C. More likely. The sampling distribution is wider for larger samples resulting in more extreme obtained means. D. Less likely. The mean of the sample will increase as the sample size increases. 38. Which of the following was NOT an advantage of repeated measures designs? A. It helps to control for extraneous variables. B. It allows us to avoid problems associated with variability from subject to subject. C. It greatly reduces required calculations by allowing us to omit outlier participants. D. It requires fewer subjects that other designs.

39. An independent measures study comparing two treatment conditions produces a t- statistic with df = 18. If the two samples are the same size, how many participants were in each of the samples? A. 9 B. 20 C. 10 D. 9.5 E. More information is needed. 40. Which of the following are true about statistical power? A. When the size of the effect in the population is large, we will have more statistical power. B. When the variability of the effect is high in the population, we will have more statistical power. Conversely, when the variability of the effect is low in the population, we will have less statistical power. C. When the sample size is high, we will have more statistical power. Conversely, when the sample size is low, we will have less statistical power. D. Running a one-tailed test gives you more power than running a two-tailed test. E. Both B. and C. F. Both A., C. and D. 41. After running their analyses, a sociologist conducting an experiment about the effect of economic incentives on political cooperation ends up with a p-value of.051. At α =.05, which of the following is the most sensible conclusion? A. At α =.05, the results are statistically insignificant, telling us that the the effect of economic incentives is also practically insignificant. B. At α =.05, the results are statistically significant, telling us that the the effect of economic incentives is also practically significant. C. At α =.05, the results are statistically insignificant. However, this does not determine the practical significance of the findings. D. At α =.05, the results are statistically significant. However, this does not determine the practical significance of the findings. 42. As the standard deviation increases, the standard error: A. Increases, resulting in a smaller test statistic. B. Decreases, resulting in a smaller test statistic. C. Increases, resulting in a larger test statistic. D. Decreases, resulting in a larger test statistic. 43. What does it mean for a result to be statistically significant?

A. The result is too large to be consistent with chance variability. B. The result proves that our study design was unbiased. C. The data from the study were within the margin of error. D. The study produced a result that is likely biased. 44. Suppose, that two independent samples each have n = 20 with sample variances of 10 and 8. Calculate the appropriate test statistic testing the null hypothesis that the variances are equal. A. 1.25 B..8 C. 1.56 D..64 45. The estimated standard error of M 1 M 2 that appears in the bottom of the independentmeasures t statistic can be interpreted as: A. a measure of the standard, or average, distance between a sample statistic (M 1 M 2 ) and the corresponding population parameter (µ 1 µ 2 ). B. a measure of how much difference is reasonable to expect between two sample means if the null hypothesis is true C. Both A. and B. D. None of these. 46. Ourtown Health Department reported that the height of women in the city is approximately normally distributed with a mean of 5 feet, 4 inches (i.e., 64 inches) and a standard deviation of 3 inches. Suppose we select a random sample of five women from our school, measure the height of each, and calculate the sample mean. If we wished to know whether the height of women at our school is typical of the height of women in Ourtown, how should we compare our sample data to information we have about the Ourtown population distribution? A. We should compare the sample mean to the population distribution of Ourtown women as we do with an individual score. B. We should compare each individual score in our sample, one at a time, to the population of individual scores. C. There really isn t a way to make any worthwhile comparison. D. We should compare this sample mean to a sampling distribution of all possible means for samples of 5 women from the population of women in Ourtown. 47. Which of the following statements about the distribution of sample means is completely correct? A. Regardless of the size of your sample, the distribution of sample means will be normal.

B. The distribution of sample means will only be normal if you draw from a population that already has a normal shape. C. The distribution of sample means will be normal if the population is normal and sample sizes are large about n = 10. D. The distribution of sample means will be normal if and only if the sample sizes are large (about n = 30 or n = 35). E. All of these are wrong in some way. 48. We want to study the mean difference in autonomy between first-born and second-born children. Instead of taking a random sample of children we take a random sample of families and sort the children into first- and second-born. The dependent variable is a measure of autonomy. To investigate the topic of interest, the experiment would most likely employ: A. a repeated measures analysis. B. a Z-test. References C. an independent measures analysis. D. Hartley s F-Max Test David Howell, Statistical Methods for Psychologists and companion site. David Howell, Fundamental Statistics for the Behavioural Sciences and companion site. Gravetter, Wallnau class textbook and companion site. Julian Parris, Psych 60 Lecture Notes and HW http://wise.cgu.edu/cltmod/index.asp