Questions and Answers of Statistics Behavioral Sciences

Calculate the power for the tests you conducted for Turck and Kirk Halls in Exercise 1 of Chapter 6. (Use the t values you calculated for that exercise as the values for δ in your power
If the sample r you calculated in Exercise 2 of Chapter 9 was equal to ρ for the population, how large a sample would you need to obtain power = .7 for a two-tailed test at the .05 level?
Suppose that you plan to match students between Turck and Kirk Halls so that the population correlation corresponds to .4. Given the d you found in part (b) of Exercise 6 and the sizes of the samples
Recalculate the required sample sizes for part (a) of Exercise 7 if the two populations are matched with ρ = .6.Data from exercise 7a. Calculate g for the comparison of the means of Turck and Kirk
Using the means and standard deviations you have already calculated for the data from the four dormitories (i.e., Turck, Dirk, Dupre, and Doty Halls), perform an analysis of variance to decide
Calculate LSD for the two experiments in Exercise 1 of the previous chapter. For which experiment is the calculation of LSD justified? Determine which pairs of means differ significantly in the
Calculate protected t tests to compare all possible pairs of the four dormitories (e.g., Turck, Kirk, etc.), using the error term for Exercise 2 of the previous chapter. Which pairs differ
What percent of the population obtains scores between 430 and 530?
What percent of the population obtains scores between 275 and 375?
A psychologist wishes to test a new learning strategy on the bottom 15% of those who took the math SAT. What cutoff score should she use to select participants for her study?
A single student is drawn at random from the population. What is the probability that this student has a score:a. Of 410 or less?b. Between 430 and 530?c. Between 275 and 375?d. In the top 5% of the
Between which two SAT scores would you find the middle:(a) 70% of the normal distribution?(b) 90% of the normal distribution?
Assume that the mean height for women at a large American university (to be viewed as a population) is 65 inches with a standard deviation of 3 inches.a. If the women are placed randomly into
Assume that the mean IQ for all 10th graders at a large high school (i.e., population) is 100 with σ = 15 and that the students are assigned at random to classes with an N of 25.a. What is the z
Given that for SAT scores, μ = 500 and σ = 100:a. Test the claim of students at Bigbrain University that they have SAT scores that are statistically significantly higher than the ordinary
Referring to the 20-point friendliness measure used in the first exercise of Chapter 1, assume that the mean score for all American college students is known to be 10, with a SD of 5 points.a. Based
Repeat Exercise 4, parts (a) and (b), for the sample from Dupre Hall. What is the same and what is different between your calculations for this exercise, and your calculations for Exercise 4?Data
This exercise is designed to give you a more direct understanding of the standard error of the mean. Create a population as follows: Get 20 identical small slips of paper or file cards. On eight of
Calculate the mean and (unbiased) SD for the following sample: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95. Assume that the SD of the population from which these
Answer these problems by calculating a t value and comparing it to the critical value for a two-tailed test at the .05 level. (Note: You can save time by using the means and standard deviations you
For Kirk Hall, compute each of the following:a. The 99% CI.b. The 95% CI.c. The 90% CI.d. Explain why the size of the CIs becomes larger as the level of confidence increases.
This exercise is based on the following data set: 1, 3, 6, 0, 1, 1, 2, 1, 4.a. Perform a t test in order to decide whether you can reject the null hypothesis of μ = 2.5 at the .05 level (two tailed)
This exercise is based on the following data set: 68.36, 15.31, 77.42, 84.00, 76.59, 68.43, 72.41, 83.05, 91.07, 80.62, 77.83.a. Perform a t test in order to decide whether you can reject the null
A politician has staked his political career on whether a new state constitution will pass. To find out which way the wind is blowing, he obtains a random sample of 100 voters a few weeks prior to
A certain business concern needs to obtain at least 20% of the market in order to make a profit. A random sample of 200 prospective buyers is asked whether they will purchase the product. What should
Use the two-sample t test to determine whether the difference in means between Turck and Kirk Halls is significant at the .05 and .01 levels, two-tailed. Given your decision with respect to the null
Repeat the previous exercise, except that this time compare Turck Hall to Dupre Hall. Would the t value based on the separate-variances formula (7.8) be smaller or larger than the pooled-variances t
Repeat Exercise 2, but this time compare Kirk Hall to Dupre Hall, and conduct only a one-tailed test at the .05 level, assuming that Kirk will have the larger mean.Data from exercise 2Repeat the
An industrial psychologist obtains scores on a job-selection test from 41 men and 31 women, with the following results: men, M = 48.75(SD = 9.0); women, M = 46.07(SD = 10.0). Test this difference for
Suppose that the industrial psychologist from the previous exercise is testing the difference in performance on the job-selection test of two different ethnic groups. Given the following data, can
Repeat Exercise 5 for the following two sets of summary statistics. In each case, determine if the results would be significant for a one-tailed as well as a two-tailed test, but compute the CI only
An educational psychologist has developed a new textbook based on programmed instruction techniques and wishes to know if it is superior to the conventional kind of textbook. He therefore obtains
For the following set of data, assume that the X score represents the participant's performance in the experimental condition and that the Y score represents the same person's performance in the
Now carry out a matched t test for the same set of data as in Exercise 8, but with the X values rearranged as shown. 1| 92 ||89 2|| 82 ||57 3 || 85 ||87 4 || 81 ||76 587 ||97 6| 93 ||79 7 68 |91 8||
Suppose that you have read the following sentence in a psychology journal: “The experimental group obtained a higher score on the recall task (M = 14.7) than did the control group (M = 11.1), and
An operator of a certain machine must turn it off quickly if a danger signal occurs. To test the relative effectiveness of two types of signals, a small group of operators is randomly divided into
Redo Exercise 5 from Chapter 7 using the rank-sum test instead of a t test. Does your statistical conclusion differ from the one you made in the previous chapter? Why would the rank-sum test not be
In Experiment 1 (see the following table), Ihno is comparing scores on a practice final exam between the students who performed most poorly on the midterm (Group 1) and those who got the highest
A psychology professor uses three different methods of instruction in three small classes, with the assignment of students to classes being random, and gives each class the same final examination.
For each of the two (separate) experiments that follow, perform the Wilcoxon test. If an experiment yields statistically significant results, also compute rc. (b) Experiment 4 X1 (a) Experiment 3 X1
Ten subjects participate in a problem-solving experiment. Two judges are asked to rate the solutions with regard to their creativity (1 = most creative, 10 = least creative). The experimenter wishes
A college dean would like to know how well he can predict sophomore grade point average for first semester freshmen so that students who are headed for trouble can be given appropriate counseling.
The data from Exercise 7 in Chapter 7 are reproduced in the following table. Calculate the mean and the unbiased standard deviations for both the experimental and control groups, and then compute the
The data from Exercises 8 and 9 in Chapter 7 are reproduced in the tables that follow.a. Compute the Pearson r for Data Set 3, Chapter 1, and test for significance at the .01 level.b. Use the z
Ten subjects participate in a problem-solving experiment. Two judges are asked to rank order the solutions with regard to their creativity (1 = most creative, 10 = least creative). The experimenter
Compute the linear regression equation for predicting Y from X for each of the data sets in Exercise 3 in Chapter 9. What proportion of the variance in Y is accounted for by X in each data set? For
Use the t value you calculated for Exercise 1 in Chapter 7 to find the point-biserial r that corresponds to the difference in means between Turck and Kirk Halls. Then use the appropriate t formula to
An industrial psychologist obtains scores on a job-selection test from 41 men and 31 women, with the following results (see Exercise 4 in Chapter 7): men, M = 48.75 (SD = 9.0); women, M = 46.07 (SD =
Another industrial psychologist asks a group of 9 assembly-line workers and 11 workers not on an assembly line (but doing similar work) to indicate how much they like their jobs on a 9-point scale (9
Suppose that the students at Bigbrain University are planning to test whether the mean math SAT score for their school is higher than the national average (μ) of 500 (assume that σ = 100). a. If
a. A politician needs 50% or more of the vote to win an election. To find out how his campaign is going, he plans to obtain a random sample of 81 voters and see how many plan to vote for him. He is
a. A personality theorist expects that two particular traits have a linear correlation on the order of .40 in the population she plans to sample. She wishes to test the null hypothesis that the
a. Calculate g for the comparison of the means of Turck and Kirk Halls (if you did not already calculate that value for Exercise 1 of Chapter 7). Use g as your estimate of d, and compute the sample
a. Calculate g from the pooled-variance t value you computed to solve Exercise 2 in Chapter 7. Use that value for g as your estimate of d, and compute the sample sizes you would need for power = .9,
Calculate the missing values in the following table, assuming that you are comparing two independent, equalsize samples with a two-tailed t test. (Note: Small = .2, Medium = .5, Large = .8.) n in
a. Calculate the power your test would have in Exercise 7 of Chapter 7 if the two sets of scores were not correlated at all in the population (use g for those data as d in your power calculation).b.
Following are two separate (hypothetical) sets of data that are somewhat exaggerated to help clarify the procedures underlying analysis of variance. In each case, the experimenter is interested in
For each of the following two experiments, calculate the means and variances for each group first, and then use those statistics to perform the ANOVA.a. Can you reject the null hypothesis for
Calculate the one-way ANOVA and determine its statistical significance for the following data: Group 2 4 23 х 30 7.2 34 29 26 5.8 6.0 6.5 7.0 14 12 15 12 15
For each of the two (separate) experiments that follow, perform the Kruskal-Wallis H test. If an experiment yields statistically significant results, compute the appropriate eta squared. (a)
The following data table comes from Exercise 4 in Chapter 8, in which a psychology professor used three different methods of instruction in three small classes. In Chapter 8 you were asked to compare
Consider the following hypothetical results, as published in a hypothetical journal: “The participants had been divided equally among three experimental conditions negative feedback, positive
Calculate both LSD and HSD for the two experiments in Exercise 3 of the previous chapter, using the harmonic mean of the three sample sizes as your value for n. What conclusions can you draw for each
For your convenience, the data from Exercise 4 from the previous chapter are reprinted in the following table:a. Using the harmonic mean of all the sample sizes as your value for n, calculate HSD for
A study using five samples finds that the mean of each sample is as follows: Sample 1 = 6.7; Sample 2 = 14.2; Sample 3 = 13.8; Sample 4 = 10.4; Sample 5 = 15.8. Suppose that HSD (with q based on α =
For this exercise, we will use Table 13.4, reprinted here, for the sample means. This time, however, imagine that the size of each sample (n) is 7 and that you do not know MSW. Fortunately, you are
In Exercise 7 of the previous chapter, the means for the negative feedback, positive feedback, and no feedback groups were X̅neg = 11.1, X̅pos = 14.7, and X̅no = 12.4, and the F ratio for the
The following table contains the statistics quiz scores for 18 students as a function of their phobia level and gender.a. Compute the two-way ANOVA for these data, and present your results in the
An industrial psychologist wishes to determine the effects of satisfaction with pay and satisfaction with job security on overall job satisfaction. He obtains measures of each variable for a total
Suppose that a 2 Ã— 2 factorial design is conducted to determine the effects of caffeine and sex on scores on a 20-item English test. The cell means are given in the following table.a.
For each of the following experiments, perform a two-way ANOVA and then the follow-up tests that are appropriate for your results. Use a graph of the cell means to explain the results you obtained.a.
Redo Exercise 7 from Chapter 7 as a one-way RM ANOVA. What is the relationship between the F ratio you calculated for this exercise and the t value you calculated for that exercise?Data from exercise
The following group means come from Exercise 4 in Chapter 12. Compute the one-way RM ANOVA for these data, assuming that there are a total of 15 blocks of (matched) participants and that SSerror = 5,
The following data come from an experiment in which each participant has been measured under three different levels of distraction (the DV is the number of errors committed on a clerical task during
Suppose that, prior to performing the clerical tasks in the experiment of Exercise 3, the first six participants took pills they thought to be caffeine but that were actually placebos; the remaining
Suppose that participants are asked to memorize a list of words that range from very abstract to very concrete. The number of words recalled of each type for each participant are shown in the
In the following problems, cards are drawn from a standard 52-card deck. Before a second draw, the first card drawn is replaced and the deck is thoroughly shuffled. Compute each of the following
The following questions refer to the throw of one fair, six-sided die.a. What is the probability of obtaining an odd number on one throw?b. What is the probability of obtaining seven odd numbers in
One hundred slips of paper bearing the numbers from 1 to 100, inclusive, are placed in a large hat and thoroughly mixed. What is the probability of drawinga. The number 17?b. The number 92?c. Either
Slips of paper are placed in a large hat and thoroughly mixed. Ten slips bear the number 1, 20 slips bear the number 2, 30 slips bear the number 3, and 5 slips bear the number 4. What is the
Imagine that you want to test whether a particular coin is biased or fair by flipping the coin four times and counting the number of times it comes up heads.a. How many different sequences can be
Apply the sign test to the data from Exercise 8 in Chapter 7, using one of the normal approximation formulas. Explain the difference in results between this exercise and the one in Chapter 7.Data
Suppose that after 6 months of a new form of treatment for chronic schizophrenia, 18 patients exhibited some improvement, 4 did not change, and 6 patients actually got worse.a. Using the sign test,
Out of 100 psychiatric patients given a new form of treatment, 60 improved, while 40 got worse.a. Use a chi-square test to decide whether you can reject the null hypothesis that the treatment is
A developmental researcher has observed that in a random sample of 60 toddlers, 27 preferred blue toys, 19 preferred red toys, and 14 preferred green toys. Perform a chi-square test of the null
At Bigbrain University, the typical grade distribution is A, 15%; B, 25%; C, 45%; D, 10%; F, 5%. The grades given by two professors are shown here. For each one (separately), test the null hypothesis
Repeat the previous exercise, except that this time there are 79 toddlers choosing among toys that come in a total of four different colors. The number of toddlers preferring each color is as
A psychologist wants to test the hypothesis that college women will do better on a particular type of problemsolving task than will college men. He obtains the following results:a. Test the null
A bond issue is to be put before the voters in a forthcoming election. An opinion poll company obtains a random sample of 200 registered voters and asks them what party they belong to and how they
Suppose that students majoring in the natural sciences, social sciences, and humanities were asked whether they were in favor of having greater student participation in academic decisions at their
Repeat the previous exercise with the data in the following table. Note that the marginal frequencies have not changed, so you do not have to recompute the expected frequencies.a. Now can you reject
Compute the median of Turck Hall from the grouped frequency distribution you created for that dorm when solving the second exercise of Chapter 2.
Compute the median and mean for Distribution 6 in Table 3.2. Why can't you find the mode of this distribution?Table 3.2 Distribution 3 6. 4 7.0 7.2 40.2 7.0 10.0 97.8 7.0 7.1 40.1 7.0 10.0 88.5 7.0
Insert the sums you found for Exercise 3 of Chapter 1 into the computing formulas given in this chapter to find σ2, σ, s2, and s for the four dorms. (We highly recommend that you also learn to
Recalculate σ2, σ, s2, and s for Dupre Hall using the definitional formulas, and compare them to the corresponding results from the previous exercise. Which type of formula (computing or
The mean of an exam is 57.3 and the standard deviation is 9.6. What will happen to the standard deviation of these scores if the instructor(a) Adds 5 points to each score?(b) Subtracts 4 points from
Forest bathing, also called Shinrin-yoku, is the practice of taking short, leisurely walks in a forest to enhance positive health. To test the usefulness of this practice, the time forest bathing per
As the level of confidence increases, what happens to the certainty of an interval estimate?
Which type of estimation (point or interval estimation) is more precise?
Privitera and Freeman (2012) constructed a scale to measure or estimate the daily fat intake of participants; the scale was called the estimated daily intake scale for fat (EDIS-F). To validate the

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