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Statistics For Psychology 6th Edition Arthur Aron, Elaine N. Aron, Elliot J. Coups - Solutions
A researcher studied the number of anxiety attacks recounted over a two-week period by 30 people in psychotherapy for an anxiety disorder. In an article describing the results of the study, the researcher reports: "The mean number of anxiety attacks was 6.84 (SD = 3.18)." Explain these results to a
In a study by Gonzaga et al. (2001), romantic couples answered questions about how much they loved their partner and also were videotaped while revealing something about themselves to their partner. The videotapes were later rated by trained judges for various signs of affiliation. Table 2-8 shows
On a measure of anxiety, the mean is 79 and the standard deviation is 12. What are the Z scores for each of the following raw scores?(a) 91.(b) 68.(c) 103.
Consider a test of coordination that has a normal distribution, a mean of 50, and a standard deviation of 10. (a) How high a score would a person need to have to be in the top 5%? (b) Explain your answer to someone who has never had a course in statistics.
Berger and colleagues (2011) conducted a telephone survey of energy drink consumption and alcohol use among adults in Milwaukee. In the method section of their article, they explain that "the study sample was comprised of individuals aged 18 or older who participated in the 2008 Greater Milwaukee
The following numbers of individuals in a company received special assistance from the personnel department last year:Drug/alcohol…………………….10Family crisis counseling………… 20Other……………………………. 20Total…………………………….. 50If you were to
On an intelligence test, the mean number of raw items correct is 231 and the standard deviation is 41. What are the raw (actual) scores on the test for people with IQs of (a) 107. (b) 83. (c) 100 To do this problem, first figure the Z score for the particular IQ score; then use that Z score to find
Six months after a divorce, the former wife and husband each take a test that measures divorce adjustment. The wife's score is 63, and the husband's score is 59. Overall, the mean score for divorced women on this test is 60 (SD = 6), the mean score for divorced men is 55 (SD = 4). Which of the two
Suppose the people living in a city have a mean score of 40 and a standard deviation of 5 on a measure of concern about the environment. Assume that these concern scores are normally distributed. Using the 50%-34%-14% figures, approximately what percentage of people have a score (a) Above 40. (b)
Using the information in problem 4 and the 50%-34%-14% figures, what is the minimum score a person has to have to be in the top (a) 2%, (b) 16%, (c) 50%, (d) 84%, (e) 98%?
A psychologist has been studying eye fatigue using a particular measure, which she administers to students after they have worked for 1 hour writing on a computer. On this measure, she has found that the distribution follows a normal curve. Using a normal curve table, what percentage of students
In the previous problem, the test of eye fatigue has a mean of 15 and a standard deviation of 5. Using a normal curve table, what percentage of students have scores (a) Above 16. (b) Above 17. (c) Above 18. (d) Below 18. (e) Below 14?
In the eye fatigue example of problems 6 and 7, using a normal curve table, what is the lowest score on the eye fatigue measure a person has to have to be in (a) The top 40%. (b) The top 30%. (c) The top 20%?
Using a normal curve table, give the percentage of scores between the mean and a Z score of (a) .58. (b) .59. (c) 1.46. (d) 1.56. (e) -.58.
Define the following terms in your own words:(a) Hypothesis-testing procedure.(b) .05 significance level.(c) Two-tailed test.
For each of the following,(a) Say which two populations are being compared.(b) State the research hypothesis.(c) State the null hypothesis.(d) Say whether you should use a one-tailed or two-tailed test and why.i. Do Canadian children whose parents are librarians score higher than Canadian children
Based on the information given for each of the following studies, decide whether to reject the null hypothesis. For each, give(a) The Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected.(b) The Z score on the comparison distribution for the
Based on the information given for each of the following studies, decide whether to reject the null hypothesis. For each, give(a) The Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected(b) The Z score on the comparison distribution for the
A psychologist studying the senses of taste and smell has carried out many studies in which students are given each of 20 different foods (apricot, chocolate, cherry, coffee, garlic, and so on). She administers each food by dropping a liquid on the tongue. Based on her past research, she knows that
A psychologist is working with people who have had a particular type of major surgery. This psychologist proposes that people will recover from the operation more quickly if friends and family are in the room with them for the first 48 hours after the operation. It is known that time to recover
What is the effect of going through a natural disaster on the attitude of police chiefs about the goodness of the people in their city? A researcher studying this expects a more positive attitude (because of the many acts of heroism and helping of neighbors), but a more negative attitude is also
Robins and John (1997) carried out a study on narcissism (self-love), comparing people who scored high versus low on a narcissism questionnaire. (An example item was, "If I ruled the world it would be a better place.") They also had other questionnaires, including one that had an item about how
Why is the standard deviation of the distribution of means generally smaller than the standard deviation of the distribution of the population of individuals?
Lee and colleagues (2000) tested a theory of the role of distinctiveness in face perception. In their study, participants indicated whether they recognized each of 48 faces of male celebrities when they were shown rapidly on a computer screen. A third of the faces were shown in caricature form, in
For a population that has a standard deviation of 10, figure the standard deviation of the distribution of means for samples of size(a) 2.(b) 3.(c) 4.(d) 9.
For a population that has a standard deviation of 20, figure the standard deviation of the distribution of means for samples of size (a) 2. (b) 3. (c) 4. (d) 9.
Figure the 95% confidence interval (that is, the lower and upper confidence limits) for each part of problem 2. Assume that in each case the researcher's sample has a mean of 100 and that the population of individuals is known to follow a normal curve.(a) 2.(b) 3.(c) 4.(d) 9.
Figure the 99% confidence interval (that is, the lower and upper confidence limits) for each part of problem 3. Assume that in each case the researcher's sample has a mean of 10 and that the population of individuals is known to follow a normal curve. (a) 2. (b) 3. (c) 4. (d) 9.
For each of the following samples that were given an experimental treatment, test whether the samples represent populations that are different from the general population:(a) A sample of 10 with a mean of 44.(b) A sample of 1 with a mean of 48. The general population of individuals has a mean of
For each of the following samples that were given an experimental treatment, test whether they represent populations that score significantly higher than the general population: (a) A sample of 100 with a mean of 82. (b) A sample of 10 with a mean of 84. The general population of individuals has a
Twenty-five women between the ages of 70 and 80 were randomly selected from the general population of women their age to take part in a special program to decrease reaction time (speed). After the course, the women had an average reaction time of 1.5 seconds. Assume that the mean reaction time for
A large number of people were shown a particular video of an automobile collision between a moving car and a stopped car. Each person then filled out a questionnaire about how likely it was that the driver of the moving car was at fault, on a scale from 0 = not at fault to 10 = completely at fault.
Define alpha and beta.
List two situations in which it is useful to consider power, indicating what the use is for each.
Based on a particular theory of creativity, a psychologist predicts that artists will be greater risk takers than the general population. The general population is normally distributed with a mean of 50 and a standard deviation of 12 on the risk-taking questionnaire this psychologist plans to use.
On a memory task in which words are learned in a random order, it is known that people can recall a mean of 11 words with a standard deviation of 4 and that the distribution follows a normal curve. A cognitive psychologist, to test a theory, modifies that task so that the words are presented in a
For each of the following studies, make a chart of the four possible correct and incorrect decisions, and explain what each would mean. Each chart should be laid out like Table 6-1, but put into the boxes the possible results, using the names of the variables involved in the study. (a) A study of
In a completed study, there is a known population with a normal distribution, μ = 25, and σ = 12. What is the estimated effect size if a sample given an experimental procedure has a mean of (a) 19. (b) 22. (c) 25. (d) 30. (e) 35? For each part, also indicate whether the effect is approximately
In a planned study, there is a known population with a normal distribution, μ = 50, and σ = 5. What is the predicted effect size (d) if the researchers predict that those given an experimental treatment have a mean of (a) 50. (b) 52. (c) 54. (d) 56. (e) 47? For each part, also indicate whether
In a planned study, there is a known population with a normal distribution, μ = 15, and σ = 2. What is the predicted mean if the researcher predicts (a) A small positive effect size. (b) A medium negative effect size. (c) A large positive effect size. (d) An effect size of d = .35. (e) An effect
Here is information about several possible versions of a planned experiment. Figure effect size for each; sketch the distributions involved, showing the area for alpha, beta, and power. (Assume all populations have a normal distribution.) Figure the power for each version.
You read a study in which the result is significant (p < .05). You then look at the size of the sample. If the sample is very large (rather than very small), how should this affect your interpretation of (a) The probability that the null hypothesis is actually true. (b) The practical importance of
Aron and colleagues (1997) placed strangers in pairs and asked them to talk together following a series of instructions designed to help them become close. At the end of 45 minutes, individuals privately answered some questions about how close they now felt to their partners. (The researchers
How does each of the following affect the power of a planned study? (a) A larger predicted difference between the means of the populations. (b) A larger population standard deviation. (c) A larger sample size. (d) Using a more extreme significance level (e.g., .01 instead of .05). (e) Using a
In each of the following studies, a single sample's mean is being compared to a population with a known mean but an unknown variance. For each study, decide whether the result is significant. (Be sure to show all of your calculations.)
Weller and Weller (1997) conducted a study of the tendency for the menstrual cycles of women who live together (such as sisters) to become synchronized. For their statistical analysis, they compared scores on a measure of synchronization of pairs of sisters living together versus the degree of
A study was done of personality characteristics of 100 students who were tested at the beginning and end of their first year of college. The researchers reported the results in the following table:(a) Focusing on the difference scores, figure the t values for each personality scale. (Assume that SD
Suppose a candidate running for sheriff in a rural community claims that she will reduce the average speed of emergency response to less than 30 minutes, which is thought to be the average response time with the current sheriff. There are no past records; so the actual standard deviation of such
A researcher tests five individuals who have seen paid political ads about a particular issue. These individuals take a multiple-choice test about the issue in which people in general (who know nothing about the issue) usually get 40 questions correct. The number correct for these five individuals
For each of the following studies using difference scores, test the significance using a t test for dependent means.
A program to decrease littering was carried out in four cities in California's Central Valley starting in August 2011. The amount of litter in the streets (average pounds of litter collected per block per day) was measured during July before the program started and then the next July, after the
A researcher assesses the level of a particular hormone in the blood in five patients before and after they begin taking a hormone treatment program. Results for the five patients are as follows:Using the .05 significance level, was there a significant change in the level of this hormone? (a) Use
Figure the estimated effect size and indicate whether it is approximately small, medium, or large, for each of the following studies:
What is the power of each of the following studies, using a t test for dependent means (based on the .05 significance level)?
About how many participants are needed for 80% power in each of the following planned studies that will use a t test for dependent means with p
For each of the following studies, say whether you would use a t test for dependent means or a t test for independent means. (a) A researcher randomly assigns a group of 25 unemployed workers to receive a new job skills program and 24 other workers to receive the standard job skills program, and
What are the approximate numbers of participants needed for each of the following planned studies to have 80% power, assuming equal numbers in the two groups and all using the .05 significance level? (Be sure to give the total number of participants needed, not just the number needed for each
Van Aken and Asendorpf (1997) studied 139 German 12-year-olds. All of the children completed a general self-worth questionnaire and were interviewed about the supportiveness they experienced from their mothers, fathers, and classmates. The researchers then compared the self-worth of those with high
Figure SDifference for each of the following studies:
For each of the following experiments, decide whether the difference between conditions is statistically significant at the .05 level (two-tailed).
A social psychologist studying mass communication randomly assigned 82 volunteers to one of two experimental groups. Sixty-one were instructed to get their news for a month only from television, and 21 were instructed to get their news for a month only from the Internet. (Why the researcher didn't
An educational psychologist was interested in whether using a student's own name in a story affected children's attention span while reading. Six children were randomly assigned to read a story under ordinary conditions (using names like Dick and Jane). Five other children read versions of the same
A developmental psychologist compares 4-year-olds and 8-year-olds on their ability to understand the analogies used in stories. The scores for the five 4-year-olds tested were 7, 6, 2, 3, and 8. The scores for the three 8-year-olds tested were 9, 2, and 5. Using the .05 level, do older children do
Figure the estimated effect size for problems (a) 4 (b) 5 (c) 6. (d) Explain what you have done in part (a) to someone who understands the t test for independent means but knows nothing about effect size.
Figure the approximate power of a t test for independent means for each of the following planned studies:
Figure the approximate power of each of the following planned studies, all using a t test for independent means at the .05 significance level, one-tailed, with a predicted small effect size:
For each of the following studies, decide whether you can reject the null hypothesis that the groups come from identical populations. Use the .05 level. Study (b) provides S, not S2.
Based on Table 9-11 from the Hazan and Shaver (1987) study, indicate for which variables, if any. (a) The Avoidants are significantly different from the other two groups. (b) The Anxious-Ambivalents are different from the other two groups. (c) The Secures are different from the other two
For each of the following studies,(a) and (b), Decide whether you can reject the null hypothesis that the groups come from identical populations. Use the .01 level.(c) Figure the effect size for each study.(d) For study (a), carry out an analysis of variance using the structural model method.
A psychologist at a private psychiatric hospital was asked to determine whether there was any clear difference in the length of stay of patients with different categories of diagnosis. Looking at the last four patients in each of the three major categories, the results (in terms of weeks of stay)
A study compared the felt intensity of unrequited love (loving someone who doesn't love you) among three groups: 50 individuals who were currently experiencing unrequited love who had a mean experienced intensity = 3.5, S2 = 5.2; 50 who had previously experienced unrequited love and described their
A researcher studying genetic influences on learning compares the maze performance of four genetically different strains of mice, using eight mice per strain. Performance for the four strains were as follows:Using the .01 significance level, is there an overall difference in maze performance among
What is the Bonferroni corrected significance level for each of the following situations?
For each of the following studies, test whether a comparison in which the researcher figures an F of 17.21 would be significant using the Scheffe method.
What is the power of each of the following planned studies, using the analysis of variance with p
About how many participants do you need in each group for 80% power in each of the following planned studies, using the analysis of variance with p
Each of the following is a table of means showing the results of a study using a factorial design. Assuming that any differences are statistically significant, for each table.(a) and (b) Make two bar graphs showing the results (in one graph grouping the bars according to one variable and in the
What is the power of the effect in the following planned studies using the analysis of variance with p
About how many participants do you need in each cell for 80% power in each of the following planned studies, using the analysis of variance with p
Each of the following is a table of means showing the results of a study using a factorial design. Assuming that any differences are statistically significant, for each table,(a) and (b) make two bar graphs showing the results (in one graph grouping the bars according to one variable and in the
A sports psychologist studied the effect of a motivational program on injuries among players of three different sports. The following chart shows the design. For each of the following possible patterns of results, make up a set of cell means, figure the marginal means, and make a bar graph of the
Kunda and Oleson (1997) studied the effect on stereotypes of counterinformation, learning about someone who is opposite to what you would expect from the stereotype. They predicted that extreme counterinformation may have a boomerang effect-making the stereotype even stronger. Participants were
For each of the following data sets, carry out an analysis of variance, including making a table of cell and marginal means and making a bar graph of the cell means. Use the .05 significance level.
Patients with two kinds of diagnoses were randomly assigned to one of three types of therapy and the effectiveness of the therapy was measured on a 1-to-15 scale (with a higher number indicating greater effectiveness). There were two patients per cell. Based on the following results.(a) Carry out
A psychologist who studies the legal system conducted a study of the effect of defendants' likability and nervousness on willingness to convict the defendant. Each participant read the same transcript, taken from an actual trial, in which the guilt or innocence of a male defendant was quite
Figure the effect size for each main and interaction effect for problems (a) 6a. (b) 6b. (c) 6c. (d) 7. (e) 8.
For each of the following scatter diagrams, indicate whether the pattern is linear, curvilinear, or no correlation; if it is linear, indicate whether it is positive or negative and the approximate strength (large, moderate, small) of the correlation.
A researcher studied the relation between psychotherapists degree of empathy and their patients satisfaction with therapy. As a pilot study, four patienttherapist pairs were studied. Here are the results:(a) Make a scatter diagram of the scores. (b) Describe in
An instructor asked five students how many hours they had studied for an exam. Here are the hours studied and the students' grades: Hours Studied Test Grade 0………………………… 52 10……………………….. 95 6…………………………
In a study of people first getting acquainted with each other, researchers examined the amount of self-disclosure of one's partner and one's liking for one's partner. Here are the results: Partner's Self-Disclosure Liking for
The following have been prepared so that data sets B through D are slightly modified versions of data set A. For each data set.(a) Make a scatter diagram.(b) Figure the correlation coefficient.(c) Figure whether the correlation is statistically significant (use the .05 significance level,
For each of the following situations, indicate why the correlation coefficient might be a distorted estimate of the true correlation (and what kind of distortion you would expect): (a) Scores on two questionnaire measures of personality are correlated. (b) Comfort of living situation and happiness
What is the power of each of the following studies using a correlation coefficient and the .05 significance level?
About how many participants are needed for 80% power in each of the following planned studies that will use a correlation coefficient and the .05 significance level?
Chapman et al. (1997) interviewed 68 pregnant inner city women and their male partners twice during their pregnancy, once between three and six months into the pregnancy and again between six and nine months into the pregnancy. Table 11-11 shows the correlations among several of their measures.
A sports psychologist working with hockey players has found that players' knowledge of physiology predicts the number of injuries received over the subsequent year. The regression constant in the linear prediction rule for predicting injuries from knowledge of physiology is 10.30 and the regression
In the Oettingen and colleagues (2001) study described earlier (in the "Prediction in Research Articles" section), in addition to studying anticipated disappointment, the researchers conducted an experiment focusing on number of plans and on taking responsibility. Their results are shown in Figure
Mize and Petit (1997) were interested in the impact of a mother's style of helping her child understand social interactions on the child's social life. These researchers arranged for 43 volunteer mothers and their 3- to 5-year-old children to be videotaped in three separate sessions. In the key
A professor has found that scores on the midterm exam in her classes predict scores on the final exam. The regression constant in the linear prediction rule for predicting final exam scores from midterm exam scores is 40 and the regression coefficient is .5. (a) Indicate the predictor variable. (b)
For each of the following, (a) through (d), determine the linear prediction rule for predicting criterion variable Y from predictor variable X. Then (e) make a single graph (with values from 0 to 10 on both axes) showing all the regression lines, labeling each by its letter. (Be sure to make your
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