Statistical Methods For Psychology 7th Edition David C. Howell - Solutions

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Millman’s golfing group is terrific for a group of amateurs. Are they ready to turn pro?Here’s the data. (Hint: Remember that the lower the score (in golf), the better!)
A major research study investigated how representative a treatment group’s decrease in symptoms was when a certain drug was administered as compared with the response of the entire population. It turns out that the test of the research hypothesis resulted in a Ztest score of 1.67. What conclusion
The night-shift workers in three of Super Bo’s specialty stores stock about 500 products in about 3 hours. How does this rate compare with the stocking done in the other 97 stores in the chain, which average about 496 products stocked in 3 hours? Are the stockers at the specialty stores doing a
Flu cases this past flu season in the Remulak school system (n = 500) were 15 per week. For the entire state, the weekly average was 16, and the standard deviation was 15.1. Are the kids in Remulak as sick as the kids throughout the state?
For the following situations, write out in words a research hypothesis:
What does the z in Z-test represent? What similarity does it have to a simple z or standard score?
When is it appropriate to use the one-sample Z-test?
In Figure 9.2 (p. 192), there is a striped area on the right side of the illustration.
What does chance have to do with testing the research hypothesis for significance?
Here’s more exploration of the significance versus meaningfulness debate:
What is the difference between significance and meaningfulness?
Why should we think in terms of “failing to reject” the null, rather than just accepting it?
Why is it “harder” to find a significant outcome (all other things being equal) when the research hypothesis is being tested at the .01 rather than the .05 level of significance?
What’s wrong with the following statements?
Given the following information and setting the level of significance at .05 for decision making, would your decision be to reject or fail to reject the null hypothesis? Provide an explanation for your conclusions.
What does the (idea of the) critical value represent?
What is statistical significance?
Why is significance an important construct in the study and use of inferential statistics?
Here’s an interesting extra-credit question. As you know, one of the defining characteristics of the normal curve is that the tails do not touch the x-axis. Why don’t they touch?
Who is the better student, relative to his or her classmates? Here’s all the information you ever wanted to know . . .
Imagine you are in charge of a program in which members are evaluated on five different tests at the end of the program. Why doesn’t it make sense to simply compute the average of the five scores as a measure of performance rather than compute a z score for each test for each individual and
Jake needs to score in the top 10% of his class to earn a physical fitness certificate. The class mean is 78, and the standard deviation is 5.5. What raw score does he need to get that valuable piece of paper?
Questions 8a through 8d are based on a distribution of scores with X ¯ = 75 and
For the following set of scores, compute standard scores. Do it using SPSS (easy) and do it manually to keep SPSS honest (not as easy as using SPSS but once you get the hang of it—easy enough). Notice any differences?
For the following set of scores, fill in the cells. The mean is 74.13, and the standard deviation is 9.98.
For a raw score of 55, the corresponding z score is +1. What’s the z score when the standard deviation is half as much, or 2.5? From this example, what can you conclude the effect of decreasing the amount of variability in a set of scores is on a standard score (given all else is equal, such as
The mean of a set of test scores is 50, and the standard deviation is
Why is a z score a standard score, and why can standard scores be used to compare scores from different distributions with one another?
Standard scores, such as z scores, allow us to make comparisons across different samples. Why?
To compute a standard score, what three bits of information do you need?
What are the characteristics of the normal curve? What human behavior, trait, or characteristic can you think of that is distributed normally? What makes you think it may be distributed normally?
Why does the null hypothesis presume no relationship between variables?
What is chance in the context of a research hypothesis? And what do we do about chance in our experiments?
What is the null hypothesis, and what is one of its important purposes? How does it differ from the research hypothesis?
What kinds of problems might using a poorly written or ambiguous research hypothesis introduce?
Go back to the five hypotheses that you found in question 1 above and evaluate each using the five criteria that were discussed at the end of the chapter.
For the following research questions, create one null hypothesis, one directional research hypothesis, and one nondirectional research hypothesis.
While you’re at the library, select two other articles from an area in which you are interested and write a brief description of the sample and how it was selected from the population. Be sure to include some words about whether the researchers did an adequate job of selecting the sample; be able
Go to the library and select five empirical research articles (those that contain actual data) from your area of interest. For each one, list the following:
Describe the steps that you would take to establish the construct validity of an observational paper-and-pencil test that assesses “thinking outside the box.”
Describe the differences among content, predictive, and construct validity. Give examples of how each of these is measured.
When testing any experimental hypothesis, why is it important that the test you use to measure the outcome be both reliable and valid?
In general terms, describe what a test would be like if it were reliable but not valid.Now, do the same for a test that is valid but not reliable.
Here’s the situation. You are in charge of the test development program for the office of state employment, and you need at least two forms of the same test to administer on the same day. What kind of reliability will you want to establish? Use the data in Chapter 6 Data Set 2 to compute the
How can a test be reliable and not valid? Provide an example. Why is a test not valid unless it is reliable?
You are developing an instrument that measures vocational preferences (what people want to do for a living), and you need to administer the test several times during the year to students who are attending a vocational program. You need to assess the test–retest reliability of the test and the
Provide an example of when you would want to establish test–retest and parallel forms reliability.
Go to the library and find five journal articles in your area of interest in which reliability and validity data are reported. Discuss the outcome measures that are used. Identify the type of reliability that was established and the type of validity and comment on whether you think that the levels
And, finally, what is the purpose of a chart or graph?
Create the worst-looking chart that you can, crowded with chart and font junk. Nothing makes as lasting an impression as a bad example.
Go to the library and find a journal article in your area of interest that contains empirical data but does not contain any visual representation of them. Use the data to create a chart. Be sure to specify what type of chart you are creating and why you chose the one you did. You can create the
Provide an example of when you might use each of the following types of charts. For example, you would use a pie chart to show the proportion of children in Grades 1 through 6 who receive a reduced-price lunch. When you are done, draw the fictitious chart by hand.
For each of the following, indicate whether you would use a pie, line, or bar chart and why.
Use the data available as Chapter 4 Data Set 3 on pie preference to create a pie chart ☺using SPSS.
Identify whether these distributions are negatively skewed, positively skewed, or not skewed at all and explain why you describe them that way.
Use SPSS to create a bar chart with one bar for each day (and warning—this may be a toughie).
A third-grade teacher wants to improve her students’ level of engagement during group discussions and instruction. She keeps track of each of the 15 third graders’ number of responses every day for 1 week, and the data are available as Chapter 4 Data Set
Here is a frequency distribution. Create a histogram by hand or by using SPSS.
A data set of 50 comprehension scores (named Comprehension Score) called Chapter 4 Data Set 1 is available in Appendix C and on the website. Answer the following questions and/or complete the following tasks:
On a spelling test, the standard deviation is equal to 0.94. What does this mean?
Compute the biased and unbiased values of the standard deviation and variance for the set of accuracy scores shown in Chapter 3 Data Set 4. Use SPSS if you can; otherwise, do it by hand. Which one is smaller and why?
How can you tell whether SPSS produces a biased or an unbiased estimate of the standard deviation?
This practice problem uses the data contained in the file named Chapter 3 Data Set 3.There are two variables in this data set:Using SPSS, compute all of the measures of variability you can for height and weight.
Find the inclusive range, the sample standard deviation, and the sample variance of each of the following sets of scores:1 5, 7, 9, 11 2 0.3, 0.5, 0.6, 0.9 3 6.1, 7.3, 4.5, 3.8 4 435, 456, 423, 546, 465
The variance for a set of scores is 36. What is the standard deviation, and what is the range?
For the following set of scores, compute by hand the unbiased estimates of the standard deviation and variance.58 56 48 76 69 76 78 45 66
Use SPSS to compute all the descriptive statistics for the following set of three test scores over the course of a semester. Which test had the highest average score? Which test had the smallest amount of variability?
In #5 just above, why is the unbiased estimate greater than the biased estimate?
For the following set of scores, compute the range, the unbiased and the biased standard deviations, and the variance. Do the exercise by hand.94, 86, 72, 69, 93, 79, 55, 88, 70, 93
Why does the standard deviation get smaller as the individuals in a group score more similarly on a test? And why would you expect the amount of variability on a measure to be relatively less with a larger number of observations than with a smaller one?
Why would you expect more variability on a measure of personality in college freshmen than you would on a measure of height?
Fill in the exclusive and inclusive ranges for the following items. High Score Low Score Inclusive Range Exclusive Range 12.1 3 92 51 42 42 7.5 6 27 26
Why is the range the most convenient measure of dispersion, yet the most imprecise measure of variability? When would you use the range?
Take a look at the following number of pie orders from the Lady Bird diner and determine the average number of orders for each week.
Use the data in Chapter 2 Data Set 4 and, manually, compute the average attitude scores (with a score of 10 being positive and 1 being negative) for three groups of individuals’ attitudes reflecting their experience with urban transportation.
For this exercise, use the following set of 16 scores (ranked) that consists of income levels ranging from about $50,000 to about $200,000. What is the best measure of central tendency and why?$199,999$98,789$90,878
Suppose you are working with a data set that has some very “different” (much larger or much smaller than the rest of the data) scores. What measure of central tendency would you use and why?
Under what conditions would you use the median rather than the mean as a measure of central tendency? Why? Provide an example of two situations in which the median might be more useful than the mean as a measure of central tendency.
Here are ratings (on a scale from 1 through 5) for various Super Bowl party foods. You have to decide which food is rated highest (5 is a winner and 1 a loser). Decide what type of average you will use and why. Do this by hand or use SPSS.
Imagine you are the CEO of a huge corporation and you are planning an expansion.You’d like your new store to post similar numbers as the other three that are in your empire. By hand, provide some idea of what you want the store’s financial performance to look like. And remember that you have to
You are the manager of a fast-food restaurant. Part of your job is to report to the boss at the end of each day which special is selling best. Use your vast knowledge of descriptive statistics and write one paragraph to let the boss know what happened today.Here are the data. Don’t use SPSS to
Compute the means for the following set of scores saved as Chapter 2 Data Set 3 using SPSS. Print out a copy of the output.
Do it by hand or use a computer program such as SPSS. Show your work, and if you use SPSS, print out a copy of the output.
Compute the mean, median, and mode for the following three sets of scores saved as Chapter 2 Data Set
By hand, compute the mean, median, and mode for the following set of 40 chemistry final scores.
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 police have identified as having problems, nine similar adolescents living in foster homes, and nine
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 second-born siblings using our scale. We do this when both siblings are adults, thus eliminating
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 take 10 psychiatric residents who are just beginning their residency and ask them to watch a
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 really reduced, then it should be more difficult to train an avoidance response in lesioned animals
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 that can be used to illustrate the material covered in this chapter.
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 Frequency 1 1 1 19 1 1 2 132 1 21 0 1 22 9 2 1 1 11 2 1 2 52 2 21 6 2 2 2 97 Note: For Race, 1 5 White; 2 5
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 Behavior (adult delinquency, childhood delinquency, hard-drug use, many sex partners) and use that as an
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) investigated the effects of elevated testosterone levels in a representative sample of U.S. adult males
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.

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Statistical Methods For Psychology 7th Edition David C. Howell - Solutions

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