STATS 50 Multiple Choice Questions

CHAPTER 9Which of the following is a fundamental difference between the t statistic and a z-score?(Points : 2) The t statistic uses the sample mean in place of the population mean. The t statistic uses the sample variance in place of the population variance The t statistic computes the standard error by dividing the standard deviation by n – 1 instead of dividing by n. All of these are differences between t and z.Question 2. 2. A sample of n=4 scores has SS=60. What is the variance for this sample? (Points : 2) 15 16 20 30Question 3. 3. A sample of n = 25 scores has a mean of M = 40 and a standard deviation of s = 10. What is the estimated standard error for the sample mean?(Points : 2) 4 2 .4 1Question 4. 4. A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 30, how many individuals were in the sample?(Points : 2) n=29 n=30 n=31 Cannot be determined from the information given.Question 5. 5. A sample is selected from a population with ? = 46, and a treatment is administered to the sample. After treatment, the sample mean is M = 48 with a sample variance of s2 = 16. Based on this information, what is the value of Cohen’s d?(Points : 2) d=0.125 d=0.25 d=0.50 Cohen’s d cannot be determined without knowing the sample size.Question 6. 6. With ? = .05, what is the critical t value for a one-tailed test with n = 15?(Points : 2) t = 1.761 t = 1.753 t = 2.145 t = 2.131Question 7. 7. A hypothesis test with a sample of n = 25 participants produces a t statistic of t = +2.53. Assuming a one-tailed test with the critical region in the right-hand tail, what is the correct decision? (Points : 2) The researcher can reject the null hypothesis with ? = .05 but not with ? = .01. The researcher can reject the null hypothesis with either ? = .05 or ? = .01. The researcher must fail to reject the null hypothesis with either ? = .05 or ? = .01. It is impossible to make a decision about H0 without more information.Question 8. 8. A sample has a mean of M = 39.5 and a standard deviation of s = 4.3, and produces a t statistic of t = 2.14. For a two-tailed hypothesis test with ? = .05, what is the correct statistical decision for this sample?(Points : 2) The researcher can reject the null hypothesis with ? = .05 but not with ? = .01 The researcher can reject the null hypothesis with either ? = .05 or ? = .01 The researcher must fail to reject the null hypothesis with either ? = .05 or ? = .01. It is impossible to make a decision about H0 without more information.Question 9. 9. CHAPTER 10If an independent-measures design is being used to compare two treatment conditions, then how many different groups of participants would be needed and how many scores would there be for each participant?(Points : 2) 1 group, 1 score each 2 groups, 1 score each 1 group, 2 scores each 2 groups, 2 scores eachQuestion 10. 10. An independent-measures study uses n = 15 participants in each group to compare two treatment conditions. What is the df value for the t statistic for this study?(Points : 2) 14 15 28 29Question 11. 11. What is the pooled variance for the following two samples?Sample 1: n = 8 and SS = 168Sample 2: n = 6 and SS = 120(Points : 2) 7 ?7 20.57 24Question 12. 12. Two samples, each with n = 5 scores, have a pooled variance of 40. What is the estimated standard error for the sample mean difference?(Points : 2) 4 8 10 20Question 13. 13. An independent-measures study with n = 6 in each sample produces a sample mean difference of 4 points and a pooled variance of 12. What is the value for the t statistic?(Points : 2) 1 2 4/?2 4/?8Question 14. 14. An independent-measures research study uses two samples, each with n = 10 participants. If the data produce a t statistic of t = 2.095, which of the following is the correct decision for a two-tailed hypothesis test?(Points : 2) Reject the null hypothesis with ? = .05 but fail to reject with ? = .01 Reject the null hypothesis with either ? = .05 or ? = .01 Fail to reject the null hypothesis with either ? = .05 or ? = .01 Cannot answer without additional informationQuestion 15. 15. Two samples, each with n = 9 scores, produce an independent-measures t statistic of t = 2.00. If the effect size is measured using r2, what is the value of r2?(Points : 2) 4/16 4/20 2/16 2/18Question 16. 16. Chapter 11A repeated-measures study uses a total of n = 10 participants to compare two treatment conditions. How many scores are measured in this study, and how many scores are actually used to compute the sample mean and the sample variance?(Points : 2) 20 measured and 10 used 20 measured and 20 used 10 measured and 10 used 10 measured and 20 usedQuestion 17. 17. The following data were obtained from a repeated-measures research study. What is the value of MD for these data?Subject 1st 2nd#1 10 15#2 4 8#3 7 5#4 6 11(Points : 2) 3 3.5 4 4.5Question 18. 18. For a repeated-measures study comparing two treatment conditions, a researcher obtains a sample of n = 9 difference scores with a mean of MD = 4 and a variance of s2 = 36. What is the value for the repeated-measures t statistic for these data?(Points : 2) 4/2 4/4 4/6 4/36Question 19. 19. A research report describing the results from a repeated-measures t test states that “t(22) = 1.71, p > .05.” From this report, what was the outcome of the hypothesis test?(Points : 2) Reject the null hypothesis with a sample of n = 23 participants Fail to reject the null hypothesis with a sample of n = 23 participants Reject the null hypothesis with a sample of n = 22 participants Fail to reject the null hypothesis with a sample of n = 22 participantsQuestion 20. 20. A researcher conducts a repeated-measures study to evaluate a treatment with a sample of n = 16 participants and obtains a t statistic of t = 1.94. The treatment is expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using ? = .05.(Points : 2) Reject the null hypothesis with a one-tailed test but fail to reject with two tails Reject the null hypothesis with either a one-tailed or a two-tailed test Fail to reject the null hypothesis with either a one-tailed or a two-tailed test Fail to reject the null hypothesis with a one-tailed test but reject with two tailsQuestion 21. 21. Compared to an independent-measures design, a repeated-measured study is more likely to find a significant effect because it reduces the contribution of variance due to ______. (Points : 2) time-related factors order effects the effect of the treatment individual differencesQuestion 22. 22. A sample of n = 9 college students is used to evaluate the effectiveness of a new Study Skills Workshop. Each student’s grade point average (GPA) is recorded for the semester before the workshop and for the semester after the workshop. The average GPA improved by MD = 0.60 points with s2 = 0.09. The researcher would like to use the sample to estimate how much effect the workshop would have for the entire college population. Which of the following is the 80% confidence interval for these data? (Points : 2) µD = 0.60 + 0.01(1.397) µD = 0.60 + 0.09(1.860) µD = 0.60 + 0.10(1.397) µD = 0.60 + 0.10(1.860)Question 23. 23. CHAPTER 12On average, what value is expected for the F-ratio if the null hypothesis is true?(Points : 2) 0 1.00 k-1 N-kQuestion 24. 24. A research study comparing three treatments with n = 5 in each treatment produces T1 = 5, T2 = 10, T3 = 15, with SS1 = 6, SS2 = 9, SS3 = 9, and ?X2 = 94. For this study, what is SSwithin?(Points : 2) 10 24 34 68Question 25. 25. In analysis of variance, what is measured by the MS values?(Points : 2) Sample variances Population variance The average distance from one mean to another. The total variability for the set of N scores.Question 26. 26. For an independent-measures ANOVA comparing three treatments with a sample of n = 5 in each treatment, what is the critical value for the F-ratio using ? = .05? (Points : 2) 3.88 3.49 3.74 3.34Question 27. 27. A researcher reports an F-ratio with df = 2, 18 from an independent-measures research study. Based on the df values, how many treatments were compared in the study, and what was the total number of subjects participating in the study?(Points : 2) 2 treatments and 19 subjects 2 treatments and 20 subjects 3 treatments and 21 subjects 3 treatments and 22 subjectsQuestion 28. 28. An analysis of variance is used to evaluate the mean differences for a research study comparing four treatments with a separate sample of n = 8 in each treatment. If the data produce an F-ratio of F = 4.60, which of the following is the correct statistical decision? (Points : 2) Reject the null hypothesis with ? = .05 but not with ? = .01 Reject the null hypothesis with either ? = .05 or ? = .01 Fail to reject the null hypothesis with either ? = .05 or ? = .01 There is not enough information to make a statistical decisionQuestion 29. 29. What is the purpose for post tests? (Points : 2) To determine whether or not a Type I error was committed To determine how much difference exists between the treatments To determine which treatments are significantly different None of theseQuestion 30. 30. CHAPTER 13In an independent-measures ANOVA, individual differences contribute to the variance in the numerator and in the denominator of the F-ratio. For a repeated-measures ANOVA, what happens to the individual differences in the denominator of the F-ratio?(Points : 2) They do not exist because the same individuals participate in all of the treatments. They are measured and subtracted out in the second stage of the analysis. Individual differences contribute to the variance in the denominator. None of the other options accurately describes individual differences in the denominator.Question 31. 31. In a repeated-measures ANOVA, the variability within treatments is divided into two components. What are they?(Points : 2) Between subjects and error Between subjects and between treatments Between treatments and error Total variability and errorQuestion 32. 32. How many separate groups of participants would be needed for an independent-measures, two-factor study with 3 levels of factor A and 4 levels of factor B?(Points : 2) 3 4 7 12Question 33. 33. The following data represent the means for each treatment condition in a two-factor experiment. Note that one mean is not given. What value for the missing mean would result in no AxB interaction? B1 B2 A1 20 30 A2 10 ?(Points : 2) 10 20 30 40Question 34. 34. What is the relationship among the separate F-rations in a two-factor ANOVA?(Points : 2) They may have different df values, but they all have the same denominator. They all have the same df values and they all have the same denominator. They may have different df values and may have different denominators. They all have the same df values, but they may have different denominators.Question 35. 35. In a two-factor analysis of variance, a main effect is defined as _____.(Points : 2) the mean differences among the levels of one factor the mean differences among all treatment conditions the mean difference between the two factors the difference between the largest treatment mean and the smallest treatment meanQuestion 36. 36. A repeated-measures analysis of variance for a study comparing three treatment conditions with a sample of n = 10 participants, produces an F-ratio of F = 5.40. For this result, which of the following is the correct statistical decision? (Points : 2) Reject the null hypothesis with either ? = .05 or ? = .01 Reject the null hypothesis with ? = .05 but not with ? = .01 Fail to reject the null hypothesis with either ? = .05 or ? = .01 There is not enough information to determine the correct decision.Question 37. 37. CHAPTER 14Which of the following Pearson correlations shows the greatest strength or consistency of relationship?(Points : 2) -0.90 +0.74 +0.85 -0.33Question 38. 38. A set of n = 5 pairs of X and Y scores has ?X = 15, ?Y = 5, and ?XY = 10. For these data, what is the value of SP? (Points : 2) -5 5 10 25Question 39. 39. The Pearson correlation is calculated for a sample of n = 20 individuals. If a hypothesis test is used to determine whether the correlation is significant, what df value would be used for the t statistic?(Points : 2) 18 19 20 21Question 40. 40. A set of n = 5 pairs of X and Y values has SSX = 16, SSY = 4 and SP = 2. For these data, what is the Pearson correlation ? (Points : 2) r = 2/64 r = 2/8 r = /2/8 r = 64/64Question 41. 41. For the linear equation Y = 2X + 4, if X increases by 1 point, how much will Y increase?(Points : 2) 1 point 2 points 3 points 4 pointsQuestion 42. 42. A set of n = 15 pairs of X and Y scores has SSX = 10, SSY = 40, and SP = 30. What is the slope for the regression equation for predicting Y from X?(Points : 2) 10/30 10/40 40/10 30/10Question 43. 43. A set of X and Y scores has MX = 4, SSX = 10, MY = 5, SSY = 40, and SP = 20. What is the regression equation for predicting Y from X? (Points : 2) Y=0.25X+4 Y=4X-9 Y=0.50X+3 Y=2X-3Question 44. 44. CHAPTER 15Which of the following best describes the possible values for a chi-square statistic?(Points : 2) Chi-square is always a positive whole numbers. Chi-square is always positive but can contain fractions or decimal values. Chi-square can be either positive or negative but always is a whole number. Chi-square can be either positive or negative and can contain fractions or decimals.Question 45. 45. What is referred to by the term observed frequencies?(Points : 2) The frequencies found in the sample data The frequencies found in the population being examined The frequencies computed from the null hypothesis The frequencies that are hypothesized for the population being examinedQuestion 46. 46. Which of the following accurately describes the chi-square distribution? (Points : 2) Symmetrical with a mean of zero Positively skewed with all values greater than or equal to zero Negatively skewed with all values greater than or equal to zero Symmetrical with a mean equal to n-1Question 47. 47. A sample of n = 100 people is classified into four categories. If the results are evaluated with a chi-square test for goodness of fit, what is the df value for the chi-square statistic? (Points : 2) 3 4 99 100Question 48. 48. Ten years ago, only 20% of the U.S. population consisted of people more than 65 years old. A researcher plans to use a sample of n = 200 people to determine whether the population distribution has changed during the past ten years. If a chi-square test is used to evaluate the data, what is the expected frequency for the older-than-65 category?(Points : 2) 10 20 40 100Question 49. 49. A researcher is conducting a chi-square test for independence to evaluate the relationship between gender and preference for three different designs for a new automobile. Each individual in a sample of n = 30 males and n = 30 females selects a favorite design from the three choices. If the researcher obtains a chi-square statistic of ?2 = 4.81, what is the appropriate statistical decision for the test? (Points : 2) Reject the null hypothesis with ? = .05 but not with ? = .01 Reject the null hypothesis with either ? = .05 or ? = .01 Fail to reject the null hypothesis with either ? = .05 or ? = .01 There is not enough information to determine the appropriate decision.Question 50. 50. A researcher used a sample of n = 50 individuals to determine whether they are any preferences between two new designs for a smart phone. If the data produce a chi-square statistic of X2 = 6.00 what decision should the researcher make?(Points : 2) There is a significant preference for either ? = .05 or ? = .01. There is a significant preference for ? = .05 but not for ? = .01. There is no significant preference for either ?= .05 or ? = .01. There is no significant preference for ? = .05 but there is for ? = .01.