Exam Practice 2
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Exam Practice 2

Course Number: PSY 203, Fall 2009

College/University: Allan Hancock College

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Practice Exam 2 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. ____ 1. A researcher is interested in the effect of St. Johns Wort on memory. A group of 25 college students is selected to participate in a research study. The average memory score obtained for the 25 students is a __________. a. sample b. statistic c. population d. parameter 2. A...

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Exam Practice 2 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. ____ 1. A researcher is interested in the effect of St. Johns Wort on memory. A group of 25 college students is selected to participate in a research study. The average memory score obtained for the 25 students is a __________. a. sample b. statistic c. population d. parameter 2. A characteristic, usually a numerical value, that describes a sample of scores is a __________. a. parameter b. statistic c. variable d. constant 3. The average score for an entire population would be an example of a __________. a. parameter b. statistic c. variable d. constant 4. After measuring a set of individuals, a researcher finds that Bob's score is three times greater than Jane's score. These measurements must come from a(n) __________ scale. a. nominal b. ordinal c. interval d. ratio 5. In a study evaluating the effectiveness of a new medication designed to control high blood pressure, one sample of individuals is given the medicine and a second sample is given an inactive placebo. Blood pressure is measured for each individual. For this study, what is the dependent variable? a. the medication b. the placebo c. blood pressure d. the individuals given the medication 6. A variable that has an infinite number of possible values between any two specific measurements is called a(n) __________ variable. a. independent b. dependent c. discrete d. continuous 7. For the following scores, what is (X)2 ? Scores: 3, 0, 5, 2 a. b. c. d. 20 38 100 400 ____ ____ ____ ____ ____ ____ ____ 8. For the following scores, what is (X)2? Scores: 2, 0, 4, 2 a. 16 b. 24 c. 64 d. (24)2 = 576 Which of the following symbols identifies the sample variance? a. s b. s2 c. d. 2 A sample of n = 5 scores has SS = 40. What is the variance for this sample? a. 40/5 = 8 b. 40/4 = 10 c. 5(40) = 200 d. 4(40) = 160 What is the variance for the following population of scores? Scores: 2, 2, 2, 2 a. 0 b. 2 c. 4 d. 16 Which set of scores has the least amount of variability? a. 11, 17, 31, 53 b. 5, 11, 42, 22 c. 145, 143, 145, 147 d. 27, 105, 10, 80 If you have a score of X = 75 on an exam, which set of parameters would give you the highest position within the class? a. = 70 and = 5 b. = 70 and = 10 c. = 60 and = 5 d. = 60 and = 10 Of the following z-score values, which one represents the most extreme location on the left-hand side of the distribution? a. z = +1.00 b. z = +2.00 c. z = -1.00 d. z = -2.00 Of the following z-score values, which one represents the location closest to the mean? a. z = +0.50 b. z = +1.00 c. z = -1.00 d. z = -2.00 For a population with = 60 and = 8, what is the X value corresponding to z = -0.50? a. -4 b. 56 ____ 9. ____ 10. ____ 11. ____ 12. ____ 13. ____ 14. ____ 15. ____ 16. ____ 17. ____ 18. ____ 19. ____ 20. ____ 21. ____ 22. ____ 23. ____ 24. c. 64 d. 59.5 A population of scores has = 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean? a. 70 b. 75 c. 85 d. 90 In N = 25 games last season, the college basketball team averaged = 74 points with a standard deviation of = 6. In their final game of the season, the team scored 90 points. Based on this information, the number of points scored in the final game was __________. a. a little above average b. far above average c. above average, but it is impossible to describe how much above average d. There is not enough information to compare last year with the average. A very bright student is described as having an IQ that is three standard deviations above the mean. If this student's IQ is reported as a z-score, the z-score would be __________. a. + 3 b. + 3 c. 3 d. cannot be determined from the information given Last week Sarah had exams in Math and in Spanish. She had a score of 45 on the Math exam and a score of 65 on the Spanish exam. For which class should Sara expect the better grade? a. Math b. Spanish c. The grades should be the same because the two exam scores are in the same location. d. There is not enough information to determine which is the better grade. The mean for any distribution corresponds to a z score of __________. a. 0 b. 1 c. N d. cannot be determined from the information given For a symmetrical population with = 100 the z-score corresponding to X = 120 would be __________. a. 1.20 b. 2.00 c. 1.00 d. cannot be determined from the information given A population has = 50 and = 10. If these scores are transformed into z-scores, the population of z-score will have a mean of __________ and a standard deviation of __________. a. 50 and 10 b. 50 and 1 c. 0 and 10 d. 0 and 1 A distribution with = 35 and = 8 is being standardized so that the new mean and standard deviation will be = 50 and = 10. When the distribution is standardized, what value will be obtained for a score of X = 39 from the original distribution? a. X = 54 b. X = 55 c. X = 1.10 ____ 25. ____ 26. ____ 27. ____ 28. ____ 29. ____ 30. ____ 31. ____ 32. ____ 33. d. impossible to determine without more information Probability values are always __________. a. greater than or equal to 0 b. less than or equal to 1 c. positive numbers d. All of the other 3 choices are correct. The binomial distribution will be approximately normal when __________. a. pn 10 b. qn 10 c. pn and qn are both 10 d. npq 10 For a population with = 80 and = 20, the distribution of sample means based on n = 16 will have an expected value of __________. a. 5 b. 15 c. 20 d. 80 Which of the following would produce a standard error of 3 points? a. n = 4 scores from a population with = 6 b. n = 9 scores from a population with = 9 c. n = 16 scores from a population with = 12 d. All three samples would produce a standard error of 3 points. Which of the following samples would have the largest standard error? a. n = 25 scores from a population with = 10 b. n = 25 scores from a population with = 20 c. n = 100 scores from a population with = 10 d. n = 100 scores from a population with = 20 In general, the standard error of M gets smaller as __________. a. sample size and standard deviation both increase b. sample size and standard deviation both decrease c. sample size increases and standard deviation decreases d. sample size decreases and standard deviation increases For a particular population a sample of n = 4 scores has a standard error of 10. For the same population, a sample of n = 16 scores would have a standard error of __________. a. 2.5 b. 5 c. 10 d. 20 A sample of n = 25 scores is determined to have a standard error of 2 points. What is the standard deviation for the population from which the sample was obtained? a. 2 b. 2/5 c. 10 d. 50 If sample size (n) is held constant, the standard error will __________ as the population variance increases. a. increase b. decrease c. stay constant ____ 34. ____ 35. ____ 36. ____ 37. ____ 38. ____ 39. ____ 40. d. cannot answer with the information given A positively skewed population has = 50 and = 20. A random sample of n = 4 scores obtained from this population has a mean of M = 55. What is the z-score corresponding to this sample mean? a. 0.25 b. 0.50 c. 1.00 d. 2.00 A hypothesis test is __________. a. a descriptive technique that allows researchers to describe a sample b. a descriptive technique that allows researchers to describe a population c. an inferential technique that uses the data from a sample to draw inferences about a population d. an inferential technique that uses information about a population to make predictions about a sample Which combination of factors will increase the chances of rejecting the null hypothesis? a. a large standard error and a large alpha level b. a large standard error and a small alpha level c. a small standard error and a large alpha level d. a small standard error and a small alpha level In a hypothesis test, an extreme z-score value, like z = +3 or z = +4, __________. a. is probably in the critical region b. means that you should probably reject the null hypothesis c. is strong evidence of a statistically significant effect d. All of the other options are correct. A sample of n = 25 individuals is selected from a population with = 80 and a treatment is administered to the sample. If the treatment has no effect, then a. the sample mean should be very different from 80 and should lead you to reject the null hypothesis b. the sample mean should be very different from 80 and should lead you to fail to reject the null hypothesis c. the sample mean should be close to 80 and should lead you to reject the null hypothesis d. the sample mean should be close 80 and should lead you to fail to reject the null hypothesis A Type I error means that a researcher has __________. a. falsely concluded that a treatment has an effect b. correctly concluded that a treatment has no effect c. falsely concluded that a treatment has no effect d. correctly concluded that a treatment has an effect The critical boundaries for a hypothesis test are z = +1.96 and -1.96. If the z-score for the sample data is z = 1.90, then what is the correct statistical decision? a. Fail to reject H1. b. Fail to reject H0. c. Reject H1. d. Reject H0. ____ 41. If a treatment has a very small effect, then a hypothesis test evaluating the treatment effect is likely to __________. a. result in a Type I error b. result in a Type II error ____ 42. ____ 43. ____ 44. ____ 45. ____ 46. ____ 47. ____ 48. ____ 49. ____ 50. c. correctly reject the null hypothesis d. correctly fail to reject the null hypothesis A researcher is predicting that a treatment will increase scores. If this treatment is evaluated using a directional hypothesis test, then the critical region for the test __________. a. would be entirely in the right-hand tail of the distribution b. would be entirely in the left-hand tail of the distribution c. would be divided equally between the two tails of the distribution d. cannot answer without knowing the value of the alpha level Which of the following will increase the power of a statistical test? a. change from .05 to .01 b. change from a one-tailed test to a two-tailed test c. change the sample size from n = 100 to n = 25 d. None of the other options will increase power. If two samples are selected from the same population, under what circumstances will the two samples have exactly the same t statistic? a. If the sample size (n) is the same for both samples. b. If the samples are the same size and have the same mean. c. If the samples are the same size and have the same mean and have the same sample variance. d. None of the other options are correct. On average, what value is expected for the t statistic when the null hypothesis is true? a. 0 b. 1 c. 1.96 d. t > 1.96 Holding everything else constant, increasing sample size __________. a. decreases standard error b. increases the magnitude of the t statistic c. increases degrees of freedom d. All of the other options are consequences of increasing sample size. With = .05 the two-tailed critical region for a sample of n = 10 participants would have boundaries of __________. a. t = 1.96 b. t = 1.833 c. t = 2.262 d. t = 2.228 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, what was the statistical decision? a. The null hypothesis was rejected and the probability of a Type I error is less than .05. b. The null hypothesis was not rejected and the probability a of Type I error is less than .05. c. The null hypothesis was not rejected and the probability of a Type II error is less than .05. d. There is not enough information to determine the decision from the hypothesis test. Even a very small treatment effect can be statistically significant if __________. a. the sample size big and the sample variance is small b. the sample size and the sample variance are both big c. the sample size is small and the sample variance is big d. the sample size and the sample variance are both small What is the pooled variance for the following two samples? Sample 1: n = 6 and SS = 200 Sample 2: n = 10 and SS = 300 a. 250 b. 500 c. 500/14 d. 500/16 One sample of n = 10 scores has a variance of s2 = 10 and a second sample of n = 10 scores has s2 = 20. If the pooled variance is computed for these two samples, then the value obtained will be __________. a. closer to 10 than to 20 b. closer to 20 than to 10 c. exactly half way between 10 and 20 d. cannot be determined without more information An independent-measures research study produces a t statistic with df = 20. What is the total number of individuals who participated in the study? a. 18 b. 19 c. 21 d. 22 For which of the following situations would a repeated-measures study be appropriate? a. Compare attitude scores for males versus females. b. Compare personality scores for individuals diagnosed with an eating disorder and those who are not diagnosed. c. Compare salary levels for college graduates and those who did not graduate from college. d. Compare reaction times before and after taking a pain medication. A repeated-measures experiment and an independent-measures experiment both produce t statistics with df = 20. Which experiment used more subjects? a. repeated measures b. independent measures c. They both used n = 21 subjects. d. They both used n = 22 subjects. A repeated-measures experiment comparing two treatment conditions uses a sample of n = 15 subjects. If the results are evaluated using a t statistic, what would be the value of df? a. 14 b. 16 c. 28 d. 29 An analysis of variance produces SStotal = 90 and SSwithin treatments = 40. For this analysis, what is SSbetween treatments? a. 50 b. 130 c. 3600 d. cannot be determined without additional information An analysis of variance is used to evaluate the mean differences for a research study comparing four treatment conditions with a separate sample of n = 5 in each treatment. The analysis produces SSwithin treatments = 32, SSbetween treatments = 40, and SStotal = 72. For this analysis, what is MSwithin treatments? a. 32/5 b. 32/4 c. 32/16 ____ 51. ____ 52. ____ 53. ____ 54. ____ 55. ____ 56. ____ 57. ____ 58. ____ 59. ____ 60. ____ 61. ____ 62. d. 32/20 In the notation for ANOVA, the letter n refers to __________ and the letter N refers to __________. a. the number of scores in each treatment, the number of scores in the entire study b. the number of scores in the entire study, the number of scores in each treatment c. the sum of the scores in each treatment, the sum of the scores for the entire study d. the sum of the scores for the entire study, the sum of the scores in each treatment For an independent-measures experiment comparing two treatment conditions with a sample of n = 10 in each treatment, the F-ratio would have df equal to __________. a. 18 b. 19 c. 1, 18 d. 1, 19 An analysis of variance produces SSbetween = 40 and SSwithin = 60. Based on this information, the percentage of variance accounted for, 2, is equal to __________. a. 40/60 = 67% b. 40/100 = 40% c. 60/40 = 150% d. 60/100 = 60% Under what circumstances are post tests necessary? a. reject the null hypothesis with k = 2 treatments b. reject the null hypothesis with k > 2 treatments c. fail to reject the null hypothesis with k = 2 treatments d. fail to reject the null hypothesis with k > 2 treatments In general the distribution of F-ratios is __________. a. symmetrical with a mean of zero b. positively skewed with all values greater than or equal to zero c. negatively skewed with all values greater than or equal to zero d. symmetrical with a mean equal to dfbetween ____ 63. A research study compares three treatments with n = 5 in each treatment. If the SS values for the three treatments are 25, 20, and 15, then the analysis of variance would produce SSwithin equal to __________. a. 12 b. 20 c. 60 d. cannot be determined from the information given ____ 64. A repeated-measures study uses a sample of n = 10 participants to evaluate the mean differences among four treatment conditions. In the analysis of variance for this study, what is the value for dfbetween subjects? a. 9 b. 27 c. 36 d. 39 ____ 65. The within treatment df for a repeated-measures ANOVA is 15. The between subject df is 5. What is the value for error df? a. 3 b. 75 c. 10 d. 20 ____ 66. For a repeated-measures ANOVA, which of the following is computed differently, compared to an independent-measures ANOVA? ____ 67. ____ 68. ____ 69. ____ 70. ____ 71. ____ 72. ____ 73. a. total SS b. between treatment SS c. within treatment SS d. the denominator of the F ratio The results of a two-factor analysis of variance produce df = 2, 28 for the F-ratio for factor A, and df = 2, 28 for the F-ratio for the AxB interaction. Based on this information, how many levels of factor B were compared in the study? a. 1 b. 2 c. 3 d. cannot be determined without additional information A two-factor research study includes two levels of factor A and three levels of factor B with a separate sample of n = 6 individuals in each treatment condition. For this study, what is the value for dfwithin treatments? a. 5 b. 15 c. 30 d. 35 In a two-factor experiment with 2 levels of factor A and 2 levels of factor B, three of the treatment means are essentially identical and one is substantially different from the others. What result(s) would be produced by this pattern of treatment means? a. a main effect for factor A b. a main effect for factor B c. an interaction between A and B d. The pattern would produce main effects for both A and B, and an interaction. A two-factor ANOVA produces an F-ratio for factor A with df = 2, 36 and an F-ratio for factor B with df = 3, 36. Which of the following describes the experiment producing these F-ratios? a. 1 level of factor A and 2 levels of factor B b. 2 levels of factor A and 3 levels of factor B c. 3 levels of factor A and 4 levels of factor B d. 6 levels for both factors A two-factor research study compares two levels of factor A and three levels of factor B. If SSA = 30, then what is the value for MSA? a. 10 b. 15 c. 30 d. cannot be determined without additional information A scatterplot shows a set of data points that are clustered close to a line that slopes down to the right. Which of the following values would be closest to the correlation for these data? a. 0.80 b. 0.40 c. -0.40 d. -0.80 In the linear equation Y = 3X + 1, when X increases by 4 points, Y will increase by __________. a. 4 points b. 7 points c. 12 points d. 13 points ____ 74. The entrance fee for a theme park is $20. Tickets for each ride and attraction are $3 a piece. Which of the following equations describes the relation between the total cost (Y) and the number of tickets purchased (X) in a single visit to the park? a. Y = 20X + 3 b. Y = 60X c. Y = 3X + 20 d. X = 3Y + 20 ____ 75. The regression equation is computed for a sample of n = 20 pairs of X and Y scores. Which set of sample characteristics would lead to the largest value for SSerror? a. r = 0.50 with SSY = 20 b. r = 0.50 with SSY = 100 c. r = 0.80 with SSY = 20 d. r = 0.80 with SSY = 100 ____ 76. Three months ago a nationwide survey indicated that 60% of the population approved of the president's foreign policy, 30% disapproved, and 10% had no opinion. A researcher plans to use a sample of n = 300 people to determine whether opinions have changed during the past three months. If a chi-square test is used to evaluate the data, what is the expected frequency for the no opinion category? a. 10 b. 30 c. 90 d. 150 ____ 77. What does it mean to obtain a negative value for the chi-square statistic? a. The observed frequencies tend to be larger than the expected frequencies. b. The expected frequencies tend to be larger than the observed frequencies. c. There are large discrepancies between the observed and expected frequencies for most categories. d. The chi-square statistic can never be negative. ____ 78. The chi-square test for goodness of fit evaluates __________. a. the relationship between two variables b. the mean differences between two or more treatments c. the shape or proportions for a population distribution d. None of the other options are evaluated by the chi-square test. ____ 79. A basic assumption for a chi-square hypothesis test is __________. a. the population distribution(s) must be normal b. the scores must come from an interval or ratio scale c. the observations must be independent d. All of the other choices are assumptions for chi-square. ____ 80. A sample of 100 people is classified by gender (male/female) and by whether or not they are registered voters. The sample consists of 60 females, of whom 50 are registered voters, and 40 males, of whom 25 are registered voters. If these data were used for a chi-square test for independence, the expected frequency for registered males would be __________. a. 15 b. 25 c. 30 d. 45 Practice Exam 2 Answer Section MULTIPLE CHOICE 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 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