Questions and Answers of A Course In Statistics With R

A psychologist operating a group home for delinquent adolescents needs to show that it is successful at reducing delinquency. He samples nine adolescents living in their parents’home whom the
It has been argued that first-born children tend to be more independent than later-born children. Suppose we develop a 25-point scale of independence and rate each of 20 first-born children and their
Nurcombe and Fitzhenry-Coor (1979) have argued that training in diagnostic techniques should lead a clinician to generate (and test) more hypotheses in coming to a decision about a case. Suppose we
Kapp, Frysinger, Gallagher, and Hazelton (1979) have demonstrated that lesions in the amygdala can reduce certain responses commonly associated with fear (e.g., decreases in heart rate). If fear is
Apply the same data to two or more software packages and note the similarities and differences in the output. How, if at all, can you resolve the discrepancies?
If you search on PsychINFO under “log-linear” you will find many studies that used such models. Find an interesting study that contains the necessary cell frequencies and write up a short example
Agresti (1990) presents data on the relationship of the assignment of the death penalty, the defendant’s race, and the victim’s race. The data follow.RaceDefendant RaceVictim DeathPenalty
Run the complete analysis on these data. What effect does adding Gender to the analysis produce? You can compare your conclusions against the results given in Pugh’s paper.
Dabbs and Morris collected data on a number of other variables, including childhood delinquency, hard-drug use, and many sex partners. Why would it be inappropriate to create a dimension labeled
Apply a log-linear model to the data from Dabbs and Morris and interpret the results.
What are the odds ratios of delinquency for the four SES/Testosterone groups in the preceding table?
Calculate the odds of being classed as an adult delinquent for each of the categories in the preceding table.
Calculate the odds ratio of an adult having a head injury as a function of whether or not that adult wears a helmet. (Why could you not do the same thing for children?)Dabbs and Morris (1990)
Maimaris et al. concluded “No child who wore a helmet at the time of the accident sustained a head injury.” Does that seem like a conclusion that would follow from your analysis?
Interpret the results of your analyses.
What is the optimal model calculated in Exercise 17.7?
Now run the analyses using SPSS HILOGLINEAR to solve for an optimal model using backward deletion.
Run the loglinear analysis using the saturated model and draw conclusions
Examine the table of cell frequencies and predict what terms must be in the model to explain the pattern of differences.
Maimaris, Summer, Browning, and Palmer (1994) reported on a study of head injuries in children and adults involved in bicycle accidents. They broke down the data on the basis of Age, whether a motor
Use SPSS HILOGLINEAR to derive the optimal model for the data in Exercise 17.1 using backward elimination. (Hint: use LogLinear/Model Selection from the menus.) Then reproduce the results using
In Exercise 17.1 Intercourse is the obvious dependent variable. What is the difference between the roles played by the Gender 3 Race interaction and the Gender 3 Intercourse interaction?
Allison (1991) offers an interesting example from a study by Morgan and Techman (1988)looking at race, gender, and the sexual intercourse for a sample of 15- and 16-year olds. The data
Make up or find an example with respect to Exercise 16.25 where the slope is not nearly 1.0.Analyze it using both the analysis of covariance and a t test on difference scores. Do either of these
I said that in any experiment where we have pretest and posttest scores we could either look at the difference scores (compared across groups) or use the pretest as a covariate. These two analyses
I initially thought of creating an analysis of variance example from the example in Chapter 14, Section 14.7. I could have used Sex and Group as the independent variables, posttest scores as the
Write up the results of Everitt’s experiment, including effect sizes.
Everitt reported data on a study of three treatments for anorexia in young girls. One treatment was cognitive behavior therapy, a second was a control condition with no therapy, and a third was a
Use the data from Mireault (1990) in the file named Mireault.dat referred to in Exercise 7.6 to run a two-way analysis of variance on the Global Symptom Index T score (GSIT) using Gender and Group as
Use the data set named in Epinuneq.dat on the instructor’s disk to examine the results of the study by Introini-Collison and McGaugh (1986) described prior to Exercises 11.28–11.31.Using any
Klemchuk, Bond, and Howell (1990) examined role-taking in children. Children were administered a battery of role-taking tasks. They were classified as being in daycare or not being in daycare, and as
Compute the energy savings per household for the data in Exercise 16.16 by subtracting this year’s bill from last year’s bill. Then run an analysis of variance on the savings scores and compare
In studying the energy consumption of families, we have broken them into three groups.Group 1 consists of those who have enrolled in a time-of-day electrical-rate system (the charge per kilowatt-hour
If you have access to SAS, use that program to analyze the data in Exercise 16.7.Add /SS1 SS2 SS3 SS4 to the end of your Model command and show thata. Type I sums of squares adjust each term in the
Draw a Venn diagram representing the sums of squares in Exercise 16.7.1.2306A1 2 3.7167B1 2 0.3500B2 1 0.4778AB11 2 0.5444AB12 1 13.6750 1.1667A1 2 3.1667B1 2 0.1667B2 1 0.8333AB11 2 0.1667AB12 1
Using the following data, demonstrate that Method I (the method advocated in this chapter)really deals with unweighted means.B1 B2 5 11 3 9 A1 14 611 910 6 11 2 A2 12 7
For the data in Exercise 16.7, the complete model isa. Show that this model reproduces the treatment and interaction effects as calculated in Table 16.3.
For the data in Exercise 16.5, the complete model isa. Show that this model reproduces the treatment and interaction effects as calculated by the method shown in Table 16.2.
Using only the SES predictors for the data in Exercise 16.7, we find .Why is this not the same as in Exercise 16.7?
Using the SES portion of the design matrix as our predictor, we find that.a. Why is this value the same as in the answer to Exercise 16.5?b. Will this be the case in all analyses of variance?
A psychologist was concerned with the relationship between Gender, Socioeconomic Status(SES), and perceived Locus of Control. She took eight adults (age 5 25 to 30 years) in each Gender–SES
Taking the data from Exercise 16.1, add the scores 5 and 8 to the Average group and the scores 2, 3, 3, and 5 to the Good group. Rerun the analysis for Exercise 16.1 using the more complete data.
For the data in Exercise 16.1,a. Calculate treatment effects and show that the regression model reproduces these treatment effects.b. Demonstrate that for the regression model is equal to for the
In this chapter we spent a lot of time with Guber’s study of educational expenditures and found that when we controlled for the percentage of students taking the SAT exam, Expend was not a
Paul Jose has a Web site referred to in the section on mediation. He discusses a problem in which he believes that stress leads to depression through a mediating path via rumination.(In other words,
As you know, the regression coefficient gives the effect of one variable holding all other variables constant. How would you view this interpretation when you have an interaction term in your model?
In Exercise 15.4 we had a data set where BlamBeh was related to later distress at time 2.When it is included as a predictor along with Stress1 and BlamPer it is no longer a significant predictor. Why
Malcarne, Compas, Epping, and Howell (1995) examined 126 cancer patients soon after they were diagnosed with cancer and at a four-month follow-up. At the initial interviews (Time 1)they collected
I was surprised to see that frequency of the behavior was not related to the likelihood of reporting. Can you suggest reasons why this might be so?
Repeat Exercise 15.31 but this time use just the dichotomous predictor Marital Status. Create a contingency table of Married/Unmarried by Report/No Report, calculate odds ratios, and compare those
The data set Harass.dat contains slightly modified data on 343 cases created to replicate the results of a study of sexual harassment by Brooke and Perot (1991). The dependent variable is whether or
It is useful to examine the effects of measurement reliability on the outcome of a regression problem. In Exercise 15.24 the variable PVLoss was actually a reasonably reliable variable.However, for
Repeat the analysis of Exercise 15.24, requesting statistics on regression diagnostics.a. What, if anything, do these statistics tell you about the data set?b. Delete the subject with the largest
Notice that in the diagram in Exercise 15.27 SuppTotl has both a direct and an indirect effect on Depression. Its direct effect is the arrow that goes from SuppTotl to DepressT. The indirect effect
In Exercise 15.24 we posited a model in which depression was a function of perceived vulnerability, social support, and age at loss. An alternative, or additional, view might be that vulnerability
A compulsive researcher who wants to cover all possibilities might throw in the total score on perceived vulnerability (PVTotal) as well as PVLoss. (The total includes vulnerability to accidents,
Use the data set Mireault.dat from Mireault (1990), described in the Appendix and found on the Web site for this book, to examine the relationship between current levels of depression and other
For the data in Exercise 15.16, compute . How well does this equation fit compared with the optimal equation? Why should this be the case?
In Exercise 15.16 the adjusted would actually be lower for five predictors than for three predictors. Why?
In Exercise 15.16 what meaning attaches to as far as the Vermont Department of Health is concerned?
The State of Vermont is divided into 10 Health Planning Districts—they correspond roughly to counties. The following data represent the percentage of live births of babies weighing under 2500 grams
Calculate the adjusted for the 15 cases in Exercise 15.12.
Use Y and from Exercise 15.10 to show that is .
Using the data in Exercise 15.4, generate and show that .
What does the Tolerance column in Exhibit 15.6 contribute to the answers in Exercises 15.7 and 15.8?
Calculate the adjusted for the data in Exercise 15.4.
A large corporation is interested in predicting a measure of job satisfaction among its employees. They have collected data on 15 employees who each supplied information on job satisfaction, level of
For the values of in Exercise 15.2, the corresponding standard errors are[0.397 0.252.052 .025]Which, if any, predictor would you be most likely to drop if you wanted to refine your regression
Refer to Exercise 15.1. Assume that b 5 [20.438 0.762.081 20.132]Interpret the results.
A psychologist studying perceived “quality of life” in a large number of cities (N 5 150)came up with the following equation using mean temperature (Temp), median income in$1000 (Income), per
Strayer, Drews, and Crouch (2006) (which we saw as a between-subjects design in Exercise 11.32) examined the effects of cell phone use on driving ability. They had 40 drivers drive while speaking on
What do you think is the importance of the fact that the “parent” who supplies the parent rating changes from child to child?
Under what conditions might you not be interested in differences among judges?
Suppose that you had no concern about the fact that one source systematically rates children higher or lower than another source. How might you evaluate reliability differently?
What do your calculations tell you about the sources of variability in this data set?
What is the reliability of this data set in terms of the intraclass correlation coefficient?
In Exercise 14.24 you probably noticed that many observations at Time 2 are missing. (This is partly because for many patients it had not yet been 3 months since the diagnosis.)a. Compare the means
In Exercise 14.24 we ignored the fact that we have pairs of subjects from the same family.a. What is wrong with doing this?b. Under what conditions would it be acceptable to ignore this problem?c.
Everitt reported data on a study of three treatments for anorexia in young girls. One treatment was cognitive behavior therapy, a second was a control condition with no therapy, and a third was a
In the data file Stress.dat, available on the Web site, are data on the stress level reported by cancer patients and their spouses at two different times—shortly after the diagnosis and 3 months
Now analyze the data in Exercise 14.22 using a mixed models approach, an appropriate form for the covariance matrix. How do those results differ from the results you found in Exercise 14.22?
The following data come from Exercise 14.20 with some observations deleted. (An entry of“999” represents a missing observation.)a. Analyze these data using a standard repeated measures analysis
Using the data from Exercise 14.20 use SPSS to run a mixed models analysis of variance, specifying an appropriate form for the covariance matrix, and compare the results with those you obtained in
Foa, Rothbaum, Riggs, and Murdock (1991) ran a study comparing different treatments for posttraumatic stress disorder (PTSD). They used three groups (plus a waiting list control)One group received
Outline the summary table for an A 3 B 3 C 3 D design with repeated measures on A and B and independent measures on C and D.
The SPSS printout in Exhibit 14.2 was obtained by treating the data in Exercise 14.10 as though all variables were between-subjects variables (i.e., as though the data represented a standard
The abbreviated printout in Exhibit 14.1 represents the analysis of the data in Exercise 14.5.a. Compare this printout with the results you obtained in Exercise 14.5.b. What does a significant F for
Run simple effects on the data in Exercise 14.14 to clarify the results.
Plot the results you obtained in Exercise 14.14.
In an investigation of cigarette smoking, an experimenter decided to compare three different procedures for quitting smoking (tapering off, immediate stopping, and aversion therapy).She took five
Suppose we had instructed our subjects to limit their summaries to 10 words. What effect might that have on the data in Exercise 14.10?
Calculate the within-groups covariance matrices for the data in Exercise 14.10.
Refer to Exercise 14.10.a. Calculate the simple effect of reading ability for children.b. Calculate the simple effect of items for adult good readers.
In a study of the way children and adults summarize stories, we selected 10 fifth graders and 10 adults. These were further subdivided into equal groups of good and poor readers(on the hypothesis
For the data in Exercise 14.6,a. Calculate all possible simple effects after first plotting the results.b. Test the simple effects, calculating test terms and adjusted degrees of freedom where
From the results in Exercise 14.7, do we appear to have reason to believe that we have met the assumptions required for the analysis of repeated measures?
For the data in Exercise 14.6,a. Calculate the variance–covariance matrices.b. Calculate using your answers to part (a).
For 2 years I carried on a running argument with my daughter concerning hand calculators.She wanted one. I maintained that children who use calculators never learn to do arithmetic correctly, whereas
To understand just what happened in the experiment involving the training of severely developmentally handicapped children (Exercise 14.3), our original experimenter evaluated a third group at the
An experimenter with only a modicum of statistical training took the data in Exercise 14.3 and ran an independent-groups t test instead, using the difference scores (training minus baseline) as the

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