Statistics For People Who Think They Hate Statistics Using R 1st Edition Neil J. Salkind, Leslie A. Shaw - Solutions

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In Chapter 19 Data Set 5 (ch19ds5.csv), you will find entries for two variables: age category(young, middle-aged, and old) and strength following weight training (weak, moderate, strong).Are these two factors independent of one another?
Here are the results of a survey that examines preference for peanut or plain M&Ms and exercise level. Are these variables related? Do the calculations by hand or using R.
Half the marketing staff of a candy company argue that all these candy bars taste the same and are barely different from one another. The other half disagrees. Who is right? The data are ready for you to analyze as Chapter 19 Data Set 4 (ch19ds4.csv).
School enrollment officials observed a change in the distribution of the number of students across grades and were not sure whether the new distribution was what they should have expected. Test the following data for goodness of fit at the .05 level.
Using the following data, test the question of whether an equal number of boys (code = 1) and girls (code = 2) participate in soccer at the elementary level at the .01 level of significance.(The data are available as Chapter 19 Data Set 3, ch19ds3.csv.) Use R or some other statistical program to
Using the following data, test the question of whether an equal number of Democrats, Republicans, and Independents voted during the most recent election. Test the hypothesis at the .05 level of significance. Do your calculations by hand.
When does the obtained chi-square value equal zero? Provide an example of how this might happen.
For any combinations of predicted and predictor variables, what should be the nature of the relationship between them?
Take a look at Chapter 18 Data Set 3 (ch18ds3.csv), where number of home sales (Number_ Homes_Sold) is being predicted by years in the business (Years_In_Business) and level of education in years (Level_Of_Education). Why is level of education such a poor contributor to the overall prediction
Time to try out multiple predictor variables. Take a look at the data shown here where the outcome is becoming a great chef. We suspect that variables such as number of years of experience cooking, level of formal culinary education, and number of different positions (sous chef, pasta station,
Check your calculation of the correlation coefficient of the relationship between coffee consumption and stress done in Chapter 17, Question 5. If you want to know whether coffee consumption predicts group membership:a. What is the predictor or the independent variable?b. What is the criterion or
Here’s where you can apply the information in one of this chapter’s tips and get a chance to predict a Super Bowl winner! Joe Coach was curious to know whether the average number of games won in a year predicts Super Bowl performance (win or lose). The X variable was the average number of games
Go to the library and locate three different research studies in your area of interest that use linear regression. It’s okay if the studies contain more than one predictor variable. Answer the following questions for each study:
Betsy is interested in predicting how many 75-year-olds will develop Alzheimer’s disease and is using as predictors level of education and general physical health graded on a scale from 1 to 10. But she is interested in using other predictor variables as well. Answer the following questions:a.
Chapter 18 Data Set 2 (ch18ds2.csv) contains the data for a group of participants who took a timed test. The data are the average amount of time the participants took on each item (Time)and the number of guesses it took to get each item correct (Correct).a. What is the regression equation for
How does linear regression differ from analysis of variance?
Chapter 17 Data Set 5 (ch17ds5.csv) contains four variables:Age (in years)Shoe_Size (small, medium, and large as 1, 2, and 3)Intelligence (as measured by a standardized test)Level_of_Education (in years)
Discuss the general idea that just because two things are correlated, one does not necessarily cause the other. Provide an example (other than ice cream and crime!).
Use the following data to answer the questions that follow. Do these calculations manuallya. Compute the correlation between age in months and number of words known.b. Test for the significance of the correlation at the .05 level of significance.c. Go way back and recall what you learned in Chapter
A study was completed that examined the relationship between coffee consumption and level of stress for a group of 50 undergraduates. The correlation was .373, and it was a two-tailed test done at the .01 level of significance. First, is the correlation significant? Second, what’s wrong with the
Use the data in Chapter 17 Data Set 4 (ch17ds4.csv) to answer the following questions. Compute the correlation coefficient manually.a. Test for the significance of the correlation coefficient at the .05 level using a two-tailed test between hours of studying and grade.b. Interpret this correlation.
Use the data in Chapter 17 Data Set 3 (ch17ds3.csv) to answer the following questions. Do the calculations manually or use R.a. Compute the correlation between income and level of education.b. Test for the significance of the correlation.c. What argument can you make to support the conclusion that
Use the data in Chapter 17 Data Set 2 (ch17ds2.csv) to answer the following questions. Do the analysis manually or by using R.a. Compute the correlation between motivation and GPA.b. Test for the significance of the correlation coefficient at the .05 level using a two-tailed test.c. True or false?
Given the following information, use Table B.4 in Appendix B to determine whether the correlations are significant and how you would interpret the results.a. The correlation between speed and strength for 20 women is .567. Test these results at the.01 level using a one-tailed test.b. The
This is the extra-credit question: For the data set named Chapter 16 Data Set 4 (ch16ds4.csv), are girls better (as evaluated by a test of skill ranging from 1 to 10, with 10 being best) than boys and, if so, under what conditions?
Use the data from Chapter 16 Data Set 3 (ch16ds3.csv) and answer the following questions about an analysis of whether level of stress and gender have an impact on caffeine consumption(measured as cups of coffee per day).a. Is there a difference among the levels of caffeine consumption for the
Using the data in Chapter 16 Data Set 2 (ch16ds2.csv) and R, complete the analysis and interpret the results for level of severity and type of treatment for pain relief. It is a 2 × 3 experiment, like the kind you created in the answer to Question 2. Hint: don’t forget to set your contrasts to
Create a drawing or plan for a 2 × 3 experimental design that would lend itself to a factorial ANOVA. Be sure to identify the independent and dependent variables.
When would you use a factorial ANOVA rather than a simple ANOVA to test the significance of the difference between the average of two or more groups?
Why is it only appropriate to do a post hoc analysis if the F ratio is significant?
The Noodle company wants to know what thickness of noodle consumers find most pleasing to their palate (on a scale of 1 to 5, with 1 being most pleasing), so the food manufacturer put it to the test. The data are found in Chapter 15 Data Set 4 (ch15ds4.csv). Turns out that there is a significant
The data in Chapter 15 Data Set 3 (ch15ds3.csv) were collected by a researcher who wants to know whether the amount of stress is different for three groups of employees. Group 1 employees work the morning/day shift, Group 2 employees work the day/evening shift, and Group 3 employees work the night
Using the data in Chapter 15 Data Set 2 (ch15ds2.csv) and R, compute the F ratio for a comparison among the three levels representing the average amount of time that swimmers practice weekly (25 hours), with the outcome variable being their time for the 100-yard freestyle. Answer the question of
Using the following table, provide three examples of a simple one-way ANOVA, two examples of a two-factor ANOVA, and one example of a three-factor ANOVA. We show you some examples—you provide the others. Be sure to identify the grouping and the test variable as we have done here.
If you are able to reject the null hypothesis based on the F, its p value, and your critical value, what do you know about the means of the different groups?
When is analysis of variance a more appropriate statistical technique to use than a test between a pair of means?
Chapter 14 Data Set 5 (ch14ds5.csv) provides you with data for two groups of adults, tested in the fall and spring during a resistance weight-lifting class. The outcome variable is bone density (the higher the score, the denser the bones) on a scale from 1 to 10. Does lifting weights work? How
Take a look at Chapter 14 Data Set 4 (ch14ds4.csv). Does shift matter when it comes to stress(the higher the stress score, the more stress the worker feels)?
Do this exercise the good old-fashioned way—by hand. A famous brand-name manufacturer wants to know whether people prefer Nibbles or Wribbles. Consumers get a chance to sample each type of cracker and indicate their like or dislike on a scale from 1 to 10. Which do they like the most?
For Chapter 14 Data Set 3 (ch14ds3.csv), compute the t value and write a conclusion as to whether there is a difference in families’ satisfaction level, measured on a scale of 1 to 15, in their use of service centers following a social service intervention. Do this exercise using R and report the
Here are the data from a study in which adolescents were given counseling at the beginning of the school year to see if it had a positive impact on their tolerance for adolescents who were ethnically different from them. Assessments were made right before the treatment and then 6 months later. Did
For Chapter 14 Data Set 2 (ch14ds2.csv), compute the t value manually and write a conclusion as to whether there was a change in tons of paper used as a function of the recycling program in 25 different districts. (Hint: Before and after become the two levels of treatment.) Test the hypothesis at
In the following examples, indicate whether you would perform a t test of independent means or dependent means.a. Two groups were exposed to different levels of treatment for ankle sprains. Which treatment was most effective?b. A researcher in nursing wanted to know if the recovery of patients was
What is the difference between a test of independent means and a test of dependent means, and when is each appropriate?
For this question, you have to do two analyses. Using Chapter 13 Data Set 5 (ch13ds5.csv), compute the t score for the difference between two groups on the test variable (named score). Then, use Chapter 13 Data Set 6 (ch13ds6.csv) and do the same. Notice that there is a difference between the two t
Using the data in Chapter 13 Data Set 4 (ch13ds4.csv) and R, test the null hypothesis that there is no difference in group means between the number of words spelled correctly for two groups of fourth graders. What is your conclusion?
Here are the results of three experiments where the means of the two groups being compared are exactly the same, but the standard deviation is quite different from experiment to experiment. Compute the effect size using Formula 13.6 and then discuss why this size changes as a function of the change
Here’s a good one to think about. A public health researcher (Dr. L) tested the hypothesis that providing new car buyers with child safety seats will also act as an incentive for parents to take other measures to protect their children (such as driving more safely, childproofing the home, etc.).
Using the data in the file Chapter 13 Data Set 3 (ch13ds3.csv), test the null hypothesis that urban and rural residents have the same attitude toward gun control. Use R to complete the analysis for this problem.
Using the following data and R, write a brief paragraph about whether the in-home treatment is equally effective as the out-of-home treatment for two separate groups. Here are the data.The outcome variable is level of anxiety after treatment on a scale from 1 to 10
Using the results you got from Question 3 and a level of significance of .05, what are the twotailed critical values associated with each result? Would the null hypothesis be rejected?
Time for some tedious, by-hand practice just to see if you can get the numbers right. Using the following information, calculate the t test statistics by hand.
Using the same data set (Chapter 13 Data Set 2, ch13ds2.csv), test the research hypothesis at the .01 level of significance that there is a difference between boys and girls in the number of times they raise their hand in class. Do this practice problem by hand, using a calculator.What is your
Using the data in the file named Chapter 13 Data Set 2 (ch13ds2.csv), test the research hypothesis at the .05 level of significance that boys raise their hand in class more often than girls. Do this practice problem by hand, using a calculator. What is your conclusion regarding the research
Here’s a list of units of toys sold by T&K over a 12-month period during 2015. Were the average sales of $31,456 (σ = $3,287) for 2016 significantly different from monthly sales in 2015? What is Cohen’s d? What is the mean difference between 2015 and 2016 sales? Which is easier to understand?
Millman’s golfing group is terrific for a group of amateurs. Are they ready to turn pro? Here are 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 z test score of 1.67. What
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 and then write out in words the corresponding null hypothesis:a. Bob wants to know whether the weight loss for his group on the chocolate-only diet is representative of weight loss in a large population of middle-aged men.
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 11.2, there is a striped area on the right side of the illustration.a. What does that entire striped area represent?b. If the striped area were a larger portion underneath the curve, what would that represent?
What does chance have to do with testing the research hypothesis for significance?
Here’s more exploration of the significance versus meaningfulness debate:a. Provide an example of a finding that may be both statistically significant and meaningful.b. Now provide an example of a finding that may be statistically significant but not meaningful.
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?a. A Type I error of .05 means that 5 times out of 100 experiments, we will reject a true null hypothesis.b. It is possible to set the Type I error rate to zero.c. The smaller the Type I error rate, the better the results.
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?
Identify whether these distributions are negatively skewed, positively skewed, or not skewed at all and explain why you describe them that way.a. This talented group of athletes scored very high on the vertical-jump task.b. On this incredibly crummy test, everyone received the same score.c. On the
Questions 8a through 8d are based on a distribution of scores with X = 75 and standard deviation = 6.38. Draw a small picture to help you see what’s required.a. What is the probability of a score falling between a raw score of 70 and 80?b. What is the probability of a score falling above a raw
For the following set of scores, compute standard scores. Do it using R (easy) and do it manually to keep R honest (not as easy as using R 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.
The mean of a set of test scores is 50, and the standard deviation is 5. 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
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.a. What are the effects of attention span on out-of-seat classroom behavior?b. What is the relationship between the quality of a marriage and the quality
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:a. What is the null hypothesis (implied or explicitly stated)?b. What is the research hypothesis (implied or explicitly stated)?c. And what
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 Chapter 8 Data Set 3 (ch8ds3.csv) 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?

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Statistics For People Who Think They Hate Statistics Using R 1st Edition Neil J. Salkind, Leslie A. Shaw - Solutions

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