Statistics For The Behavioral Sciences 8th Edition Frederick J Gravetter, Larry B. Wallnau - Solutions

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A sociologist assembles a dataset consisting of the poverty rate, per capita income, serious crime rate, and teen birth rate for the 50 states of the United States.a. How many variables are in this dataset?b. What is an observational unit in this dataset?c. What is the sample size for the dataset?
Refer to Case Study 1.6. Go through the five steps listed under “The Discovery of Knowledge” in Section 1.3, and show how each step was addressed in this study?
Refer to Case Study 1.5. Explain what mistakes were made in the implementation of steps 4 and 5 of “The Discovery of Knowledge” when USA Today reported the results of this study.
Suppose you were to read the following news story:“Researchers compared a new drug to a placebo for treating high blood pressure, and it seemed to work. But the researchers were concerned because they found that significantly more people got headaches when taking the new drug than when taking the
Give an example of a question you would like to have answered, such as whether or not eating chocolate helps to prevent depression. Then explain how a randomized experiment or an observational study could be done to study this question.
Why was the study described in Case Study 1.5 conducted as an observational study instead of an experiment?
In this chapter, you learned that cause and effect can be concluded from randomized experiments but generally not from observational studies. Why don’t researchers simply conduct all studies as randomized experiments rather than observational studies?
A headline in a major newspaper read, “Breast-fed youth found to do better in school.”a. Do you think this statement was based on an observational study or a randomized experiment? Explain.b. Given your answer in part (a), which of these two alternative headlines do you think would be
Explain what is meant by “data snooping.”
The CNN website sometimes has a small box called “Quick vote” that contains a question about an interesting topic in the news that day. For example, one question in February 2010 asked “Should the U.S. military let gays and lesbians serve openly?” Visitors to the website are invited to
Refer to Exercise 1.33. The Roper Organization selected a random sample of adults in the United States for this poll.Suppose listeners to a late-night radio talk show were asked to call and report whether or not they had ever seen a ghost.a. What is this type of sample called?b. Do you think the
Refer to Exercise 1.33. What is the risk of someone in this age group having seen a ghost?
The Roper Organization conducted a poll in 1992 (Roper, 1992) in which one of the questions asked was whether or not the respondent had ever seen a ghost. Of the 1525 people in the 18- to 29-year-old age group, 212 said “yes.”a. What is the approximate margin of error that accompanies this
A random sample of 1001 University of California faculty members taken in December 1995 was asked, “Do you favor or oppose using race, religion, sex, color, ethnicity, or national origin as a criterion for admission to the University of California?” (Roper Center, 1996). Fifty-two percent
Case Study 1.6 reported that the use of aspirin reduces the risk of heart attack and that the relationship was found to be “statistically significant.” Does either of the cautions in the “moral of the story” for Case Study 1.7 apply to this result? Explain.
Refer to the study in Exercises 1.28 and 1.29, comparing the percentage of smokers who quit using a nicotine patch and a placebo patch. Refer to the definition of statistics given on page 1, and explain how it applies to this study.
Refer to the study in Exercise 1.28, in which there was a statistically significant difference in the percentage of smokers who quit using a nicotine patch and a placebo patch. Now read the two cautions in the “moral of the story” for Case Study 1.7. Discuss each of them in the context of this
Dr. Richard Hurt and his colleagues (Hurt et al., 1994) randomly assigned volunteers wanting to quit smoking to wear either a nicotine patch or a placebo patch to determine whether wearing a nicotine patch improves the chance of quitting. After 8 weeks of use, 46% of those wearing the nicotine
An article in the Sacramento Bee (March 8, 1984, p. A1) reported on a study finding that “men who drank 500 ounces or more of beer a month (about 16 ounces a day) were three times more likely to develop cancer of the rectum than nondrinkers.” In other words, the rate of cancer in the
Refer to Exercise 1.25, comparing vegetarians and nonvegetarians for two causes of death. Were base rates given for the two causes of death? If so, what were they? If not, explain what a base rate would be for this study.
An article in the magazine Science (Service, 1994) discussed a study comparing the health of 6000 vegetarians and a similar number of their friends and relatives who were not vegetarians. The vegetarians had a 28% lower death rate from heart attacks and a 39% lower death rate from cancer, even
Refer to Exercise 1.22.a. Create a five-number summary for the women’s responses. Show how you found your answer.b. Use your five-number summary to describe in words the exercise behavior of this group of female students.
Refer to Exercise 1.22.a. Create a five-number summary for the men’s responses.Show how you found your answer.b. Use your five-number summary to describe in words the exercise behavior of this group of male students.
Students in a statistics class at Penn State were asked,“About how many minutes do you typically exercise in a week?” Responses from the women in the class were 60, 240, 0, 360, 450, 200, 100, 70, 240, 0, 60, 360, 180, 300, 0, 270 Responses from the men in the class were 180, 300, 60, 480, 0,
Refer to Case Study 1.6, in which the relationship between aspirin and heart attack rates was examined. Using the results of this experiment, what do you think is the base rate of heart attacks for men like the ones in this study? Explain.
Explain what is meant by a “false positive” in the context of conclusions in statistical studies.Chapter Exercises
A (hypothetical) study of what people do in their spare time found that people born under the astrological sign of Aries were significantly more likely to be regular swimmers than people born under other signs. What additional information would you want to know to help you determine if this result
Explain the distinction between statistical significance and practical significance. Can the result of a study be statistically significant but not practically significant?
A randomized experiment was done in which overweight men were randomly assigned to either exercise or go on a diet for a year. At the end of the study there was a statistically significant difference in average weight loss for the two groups. What additional information would you need in order to
Suppose that an observational study showed that students who got at least 7 hours of sleep performed better on exams than students who got less than 7 hours of sleep. Which of the following are possible confounding variables, and which are not? Explain why in each case.a. Number of courses the
Read Case Study 1.5. Give an example of a confounding variable that might explain why elderly people who attended religious services might have lower blood pressure than those who did not. Do not use one of the variables already mentioned in the Case Study.
For each of the studies described, explain whether the study was an observational study or a randomized experiment.a. A group of 100 students was randomly divided, with 50 assigned to receive vitamin C and the remaining 50 to receive a placebo, to determine whether or not vitamin C helps to prevent
For each of the examples given here, decide whether the study was an observational study or a randomized experiment.a. A group of students enrolled in an introductory statistics course were randomly assigned to take either a webbased course or a traditional lecture course. The two methods were
A proposed study design is to leave 100 questionnaires by the checkout line in a student cafeteria. The questionnaire can be picked up by any student and returned to the cashier.Explain why this volunteer sample is a poor study design.
A popular Sunday newspaper magazine often includes a yes-or-no survey question such as “Do you think there is too much violence on television?” or “Do you think parents should use physical discipline?” Readers are asked to mail their answers to the magazine, and the results are reported in
About how many people would need to be in a random sample from a large population to produce an approximate margin of error of .30 or 30%?
In Case Study 1.3, the margin of error for the sample of 496 teenagers was about 4.5%. How many teenagers should be in the sample to produce an approximate margin of error of .05 or 5%?
A telephone survey of 2000 Canadians conducted March 20–30, 2001, found that “Overall, about half of Canadians in the poll say the right number of immigrants are coming into the country and that immigration has a positive effect on Canadian communities. Only 16 percent view it as a negative
A CBS News poll taken in December 2009, asked a random sample of 1048 adults in the United States, “In general, do you think the education most children are getting today in public schools is better, is about the same, or is worse than the education you received?” About 34% said “Better,”
as an example, explain the difference between a population and a sample.
Using Case Study
Refer to Case Study 1.3, in which teens were asked about their dating behavior.a. What population is represented by the random sample of 602 teens?b. What population is represented by the 496 teens in the sample who had dated?
The risk of getting lung cancer at some point in one’s life for men who have never smoked is about 13 in 1000. The risk for men who smoke is just over 13 times the risk for nonsmokers. (Source: Villenueve and Lau, 1994)a. What is the base rate for lung cancer in men over a lifetime?b. What is the
In recent years, Vietnamese American women have had the highest rate of cervical cancer in the country. Suppose that among 200,000 Vietnamese American women, 86 developed cervical cancer in the past year.a. Calculate the rate of cervical cancer for these women.b. What is the estimated risk of
is as shown.a. What is the median height for these women?b. What is the range of heights—that is, the difference in heights between the shortest woman and the tallest woman?c. What is the interval of heights containing the shortest one-fourth of the women?d. What is the interval of heights
A five-number summary for the heights in inches of the women who participated in the survey in Case Study
Refer to the data and five-number summaries given in Case Study 1.1. Give a numerical value for each of the following.a. The fastest speed driven by anyone in the class.b. The slowest of the “fastest speeds” driven by a male.c. The speed for which one-fourth of the women had driven at that
27. First-bom children tend to develop language skills faster than their younger siblings. One possibile explanation for this phenomenon is that first-boms have undivided attention from their parents. If this explanation is correct, then it is also reasonable that twins should show shower language
1. Use an ANOVA with a = 05 to determine whether there are any significant mean differences among the three groups of birds?b. Compete n', the percentage of variance explained by the group differences, for these data.e. Uve the Tukey HSD pusttest to determine which groups are significantly
26. One possible explanation for why some birds migrate and others maintain year round residency in a single location is intelligence. Specifically, birds with small brains, relative to their body ssze, are simply not smart enough to find food during the winter and must migrate to warmer climates
25. The following data represent the results from an"independent measures study comparing two frestment conditionsa. Use an independent-measures Sest with a = 05 to determine whether there is a significant mean difference between the two treatments.In Use an ANOVA with a = 05 to determine whether
24. The following values summarize the results froen za independent-measures study comparing two- treatment conditionsa. Use an independent-measures I test with o. - 05 to determine whether there as a significant mean difference between the two treatment.b. Use an ANOVA with a = 05 16 determine
23. The following data were obtained from an independent-measures research study comparing there treatment conditions. Lhe an ANOVA with a = 35 to determine Whether there are any significant mean differences:among the treatments.Treatment-2 57 N=14₲= 42 6***- 182 24 2Y- 12 T-10 55 - 14 55= 9 55-
22. A developmental psychologist ik examining the development of language skills from ape 2 10 age 5 Four different groups of children are obtained, one for ench age, with i = 13 children in each group. Each.chill is given a language skills assessment test The resulting data were unalyzed with an
21. A pharmaceutical company has developed a drug that is expected in reduce hainget. To test the drug, three samples of mats are selected with n - 10 in each sample The first sample receives the drug every day The second sample is given the drag once a week, and the third sample receives no drug
20. The Telbraing summary Gible presents the results from in ANOVA comparing three treatment conditions with n - 12 participants in each condition Complete all missing Values (Hinr. Start with the di column.)Source Between Treatments Within Treatments 117
19. There is some evidence that high school students Jostify cheating in class on the basis of poor toucher skills or low levels of teacher caring (Munlock, Miller, and Kohlhurd. 2001). Students appear to rationalize their illicit behavior based on perceptions of huw their teachers view chenting.
18. The following data are constructed so that all three treatments have exactly the same mean, M = 4;a. Before you begin any calculations, predict whal value should be obtained for 55 ........ (Hint: How big are the differences between treatments?)h. Calculate SS , and SS ....,. You should find
17. In the previous problem, the total 55 was partitioned into two components. Ssaa .... and 35 ...., To cmale the following data, we started with the scores in problem Iti but eliminated all of the within-treatments variability. (Note that all the scores in each treatment aro equal to the
16. Recent recurch indicates that she effectiveness of anti-depressand medication is directly related to the severity of the depression ( Khan. Brodhead, Kolts, & Brown.2005). Based on pre treuunent depression sonres, patiens were insded into four groups based on their level of depression. After
15. The results from an independent-mensures research study andicate that there are significant differences between treatments, F(3, 36) - 3.28.p
14. A researcher reports an F.ratio with df - 2. 24 for an independent-measures research study.1. How many treatment conditions were compared an the snady?b. How many subjects participated in the entire study?
13. Thy dann front problem 12 show significant differences between treatments. To construct the following data.we stuned with the numbers in problem 12 but we inerteed the variance within each sample.Specifically, we kept the same meus as in problem 12 but we'spread out the scores inside each of
12. The following data were obtained in a study using three separate samples to compare shrie different treatments.a. Use an analysis of varande with u =, 05 to deter-mine whether there are any significant differences among the treatments.b. Compute the value for n' for these duin.Treatingris-4 N=
11. In the preceding problem, the three sample means we close together and there are no simeficant mean differences. To construct the following dum, we Started with the scores in problemi 10, then increased the size of the mean differences. Specifically, we Inwered the antallest menn by subtracting
h. The following dma are from an experimem comparing thece treatment conditions with a separate sample of₼ =4 in cady treatmenta. Usc im ANOVA with a - 06 to determine whether there are any significant differences among the three freutmers, h. Compote To for these dafat Treatment-2 7N-12 65 G-60
9. In the previous problem the treatment were significantly different primanty because the meun for sample HIE i noticeably different from the other two- samples(Mi = I. M. - 2. and M. - 6). For the following dini we have taken the scores from problem & and reduced the differences between
R. The following dara represent the results from an independent-measures experiment comparing three.treatment conditions. Use an analysis of variance wich a = 05 to determine whether these dat see sufficient to conclude that there are significant differences"between the treatments.Treatment Fi2
7. The following data represent the results from an independete-measures Sody comparing three treatments,a. Compute $5 for the set of 3 treatment menm.(Use the three means as a set of n = 3 scores and compute SS, h. Using the result from parta, compute af 55 -.....Note that this value is equal to
6. A research study comparing three treatment conditions produced means of MY = 2. M, = 4, and M, = 6.a. Compute the variance for the set of three mennes,(Treat the means as a sample of n = 3 values and compute the sample variance.)b. Now we will change the third mean from My - 6 to M3 - 15. Notice
5. Posttests are done after an ANOVA ..a. What is the purpose for posnieszs?b. Explain why you would nut do posttests If the analysis is comparing only two treatmentsc. Explain why you would not do posttests if the decision froen the ANOVA was to fail to reject the null hypothesis.
4. Explain why you should use ANOVA instead of several tests to evaluate mean differences when an experiment consists of Three or more treatment conditions.
3. Several factors influence the size of the F-ratio. For each of the following, indicate whether it would influence the numerator or the denominator of the F-rano, and indicate whether the size of the F ratio would increase of decrease,a. Increase the differences between the sample meansb.
2. Describe the similarities between an Ficio and a statistic.
1. Explain why the expected value for an Fratto is equal to 1.00) when there Is no treatment effect
25. 1e Chiquier 1 1. problem 22 presented dots comparing the accunicy of Olympe marksmen los shots firedl during heartbeat compared to shots fired between heartbeat. The dass are presented again bere During Between Participant Heartbeats Heartbeats 90 US FUse the dina so estimate how much efters
24. Problem 16 in Chapter Il described a wody examining the effect of citing oatmeal regulaaty an cholesterol.Cholesterol was measured before and after alling colmeal to the diet of a sample of n = 9 participants.For this sample, cholesterol scores averaged Mp - 16 points border with the noumed
23. A research study has deinesieotratell that self-brygmosh can be an effective tremmes for allergies (Langenitz.Izakovic, & Wyler 2005) The researchers recruited il sample of patients with modemte io severe allergic Teuctions. The patients were trained so focus their minds on a specific place,
22. Problem 12 in Chapter IT presented data from a andy testing the effectiveness of Ritalin for increating attention span for children with ADHD: Results from a sample of w = 25 chaidren showed an average increase of titention span of M ,, = 6.8 minutes with a standund deviation of } = 5.5 aner
21. A researcher would like to determine how physical endurance is affected by a common berbal supplement.The researcher measures endurance for a sample of it - 9 participants. Each individual w then given a 30-day supply of the herbs and, I mooth luier.endurance is meseured again For this sample,
20. A researcher would like so estimate how much reaction tune 35 affected by a common over-the-counter cold medication, The researcher theasunes.reaction time for a sample of w - 36 particiants. Each is then given a dose of the cold medicatice and reaction.lime is measured again For this sample,
19. Problem 23 m Chapter 10) desconel a study demonstrating that elderly people who own dogs are less likely to pay visite to their doctors than are those who do not own pets The data are presented again here Number of Doctor White in Past Year Control Group Dog Owner 7 4 Use these data to estimate
18. Problem 15 in Chapter 10 described a study by Laughlin, Zander, Knievel, and Tan (2003) showing than groups of three people consistently outperformed the best of the individuals working alose on a letter --De-numbers solstibition problem. The following data describe the number of trials seeded
17. Problem 14 in Chapter 10 described a study by Rozis, Hauer, sad Catanese (2003) comparing allitindes forward eming for male and tensite college studenty, The results showed that females are nach more concerned about weight gain and other negative Aspects of eating than the men, The following
16. People's handshakes seem to be related to other aspects of their personalities (Chaplin, Phillipe".Brown. Clanton, & Stein, 20KW) For example, a firm handshake in megintively related to shyness To measure the magnitude of this effect, n' researcher obtained a simple of n = 11 people who were
15. Research result suggest that children who show high level of stimulanon seckiag as preschoolers. will also show higher IOs as young adolescents Raine, Reynolds, Verables, and Medmek, 2002). In un attempt to evaluate the size of this effect, a researcher obtained measures of stimulanon seeking
14. There is some evidenep suggesting that you are likely 4 improve your test score if you rothink and changit answers on a multiple-choice exam (lolinstan, 1975), To examine this phenomenon, a feather give the same final exam to mo sections of a psychology course The shadems in one section went
13. Example 10.1 (page 318) presemed a research szady demonstrating that high school students who regularly witched Sesame Street as children huf higher grades than their peers who did not watch the progmitt(Anderson, Huston, Wright, & Colling, 19982 Dne sample of n - 10 students who wakbed the
SS - 430 and the average for the younger children was M = 35.4 with $$ = 410. Lving these dotila. Make a point estimate of the population mean difference in fine motor skilleb. Make an imerval estimate so you are 95% confident that the real mean difference is in your interval.c. Make an interval
12. A developmental poychologist would like to determine bow imich fine motor skill improves for children from age 3 10 age 4. A random sample of m - 15 3-year-old children and a second sample of a - 15 4-year-olds me obtained. Each child is given a manual dexterky test that measures fine moby
IL. A common test of short term memory tempiires participants no repeat a random string of digit that was presented a few seconds carlier. The number of idigits #increased on cach trial until she pervon begins To make mistakes The longest string that can be reported accurately determines the
10. Standardized tearmures seem to indicme that thet-average level of anxiety link increased gradually over the past 30 years (Twenge, 2000) In the 1950. the uverige scome on the Child Manifest Anxiety Scale was p = 15:1. A sample of n - 16 of today's childien produce, a mean score of M = 23.3 with
9. Problem 18 in Chapter 9 described a study \bowing that children who attended a high-quality dayeure program before they coter school perform better on mith jests than children who do not have daycare experience The data showed that i sample of " = 35 children who attended day care before
& Problem 10 in Chapter 9 described a study by Hartow(1959) in which ant ant monkeys were placed in cages with rio artificial "mothers," One mother was made of wire mesh and had a bottle from which the infant could feed, and the second mother was made of son terry cloth but did not provide my food
7. A sample of it - 9 scores is obuinci! from im unknown population, The sample mean it M = 40 with a standard deviation of 4 6.i. Use the sunple data to make inn 8055 confidence interval estimate of the umknoun population meanb. Make 4 90% confidence interval estimate of p.e Make 4 95% confidence
6. An elementary school principal would like to know how many hours the students spend watching TV cach diy. A simple of w - 25 chiktren is selecied, and a wurvey is sent to each child's parents. The results indicate an average of M = 3.1 hours per day with a standard deviation of = = 3.4ka. Make a
5. For the following studies, state whether estimation of hypothesis testing is required, Alea, le an independent-or # repealed-measures / statistic appropriate !a. A researcher would like to determine whether there is any difference in the amount of homework between senior year of high school and
4. A researcher has construconil it 8086 confidence interval of p - 45 + 8, using a sample of it - 25 sentesa. What would happen bo the width of the interval if the researcher had used a larger sample xixe?(Assume other factors are bold constant. )b. What would happen to the width of the interval
3. Explain the trade off between precisinn and ccefidence for interval estimates
2. Explain why it would por be reasonable to use estimation aher à hypothesis test for which the"Jecisions was "fail to reject HE !!!

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Statistics For The Behavioral Sciences 8th Edition Frederick J Gravetter, Larry B. Wallnau - Solutions

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