A baseball pitcher, concerned about losing speed from his fastball, undertook a new training regimen during the offseason. His team's pitching coach measured the speed of 20 random fastballs (in miles per hour) thrown by the pitcher during spring training, and compared it with a sample of 20 random fastballs thrown during the pitcher's last five starts in the previous season. The results are shown in the following table. Assume that the pitcher's fastball speeds had a standard deviation of 2.9 miles per hour both before and after the training regimen and that the speeds for both time periods are normally distributed. Let the pitcher's fastball speeds in the previous season be the first sample, and let the pitcher's fastball speeds in spring training be the second sample. At the 0.05 level of significance, is there evidence that the pitcher is throwing fastballs at higher speeds? Find the test statistic, rounded to two decimal places, and the p-value, rounded to three decimal places.             Last Season's Fastball This Season's Fastball 92 90     91 95     96 93     94 94     92 91     94 95     92 97     95 92     94 97     93 92     96 93     89 92     95 97     94 93     91 95     95 96     94 92     94 97     90 99     95 93

An office manager suspects that audio stimulation while working increases their employees’ productivity. They randomly assigned 60 employees across three different groups: one listened to music, one listened to news radio, and one listened to no audio stimulus while working. The manager then measured productivity of the employees (e.g., highly productive, moderately productive, a little productive, not at all productive). What statistical test should they use to analyze their data? (note: you have a flowchart that will help you make this choice) a. Wilcoxon signed-ranked test b. Repeated measures ANOVA c. Kruskal-Wallis test d. One-way ANOVA

A statistical program is recommended. The National Football League (NFL) records a variety of performance data for individuals and teams. To investigate the importance of passing on the percentage of games won by a team, the following data show the conference (Conf), average number of passing yards per attempt (Yds/Att), the number of interceptions thrown per attempt (Int/Att), and the percentage of games won (Win%) for a random sample of 16 NFL teams for one full season. Team Conf Yds/Att Int/Att Win% Arizona Cardinals NFC 6.5 0.042 50.0 Atlanta Falcons NFC 7.1 0.022 62.5 Carolina Panthers NFC 7.4 0.033 37.5 Cincinnati Bengals AFC 6.2 0.026 56.3 Detroit Lions NFC 7.2 0.024 62.5 Green Bay Packers NFC 8.9 0.014 93.8 Houstan Texans AFC 7.5 0.019 62.5 Indianapolis Colts AFC 5.6 0.026 12.5 Jacksonville Jaguars AFC 4.6 0.032 31.3 Minnesota Vikings NFC 5.8 0.033 18.8 New England Patriots AFC 8.3 0.020 81.3 New Orleans Saints NFC 8.1 0.021 81.3 Oakland Raiders AFC…

A physical therapist wanted to know whether the mean step pulse of men was less than the mean step pulse of women. She randomly selected 54 men and 70 women to participate in the study. Each subject was required to step up and down a 6-inch platform. The pulse of each subject was then recorded. The following results were obtained. Two sample T for Men vs Women N Mean StDev SE Mean Men Women 98% CI for mu Men - mu Women (- 12.20, - 1.00) T-Test mu Men = mu Women (vs H2 O C. Ho: H1 = H2; Ha: H1 #H2 (b) Identify the P-value and state the researcher's conclusion if the level of significance was a = 0.01. What is the P-value? P-value =

Researchers compared two groups of competitive rowers: a group of skilled rowers and a group of novices. The researchers measured the angular velocity of each subject’s right knee, which describes the rate at which the knee joint opens as the legs push the body back on the sliding seat. The sample size ?, the sample mean, and the sample standard deviation for the two groups are given below.   Group N x̄ s Skilled 16 4.2 0.6 Novice 16 3.2 0.8 Construct the 99% confidence interval for the difference between the groups. How does this confidence interval relate to the conclusion of your test?

In ongoing economic analyses, the federal government compares per capita incomes not only among different states but also for the same state at different times. Typically, what the federal government finds is that "poor" states tend to stay poor and "wealthy" states tend to stay wealthy. Would we have gotten information about the 1999 per capita income for a state (denoted by y) from its 1980 per capita income (denoted by x)? The following bivariate data give the per capita income (in thousands of dollars) for a sample of sixteen states in the years 1980 and 1999 (source: U.S. Bureau of Economic Analysis, Survey of Current Business, May 2000). The data are plotted in the scatter plot in Figure 1. Also given is the product of the 1980 per capita income and the 1999 per capita income for each of the sixteen states. (These products, written in the column labelled "xy", may aid in calculations.) Florida Nevada West Virginia Hawaii Arkansas Utah Kansas Montana North Dakota Nebraska…

An automobile dealer conducted a test to determine if the time in minutes needed to complete a minor engine tune-up depends on whether a computerized engine analyzer or an electronic analyzer is used. Because tune-up time varies among compact, intermediate, and full-sized cars, the three types of cars were used as blocks in the experiment. The data obtained follow. Analyzer Computerized Electronic Compact 50 41 Car Intermediate 56 44 Full-sized 62 47 Use a = 0.05 to test for any significant differences. State the null and alternative hypotheses. O Ho: Hcompact * HIntermediate * HFull-sized Ha: "Compact = HIntermediate = 4Full-sized O Ho: HComputerized * HElectronic Ha: HComputerized = HElectronic O Ho: HComputerized = HElectronic Ha: "Computerized * HElectronic O Ho: HComputerized = HElectronic = "Compact = HIntermediate = "Full-sized H.: Not all the population means are equal. O Ho: HCompact = HIntermediate = HFull-sized Hai H compact * HIntermediate * HFull-sized Find the value of…

Researchers compared two groups of competitive rowers: a group of skilled rowers and a group of novices. The researchers measured the angular velocity of each subject’s right knee, which describes the rate at which the knee joint opens as the legs push the body back on the sliding seat. The sample size ?, the sample mean, and the sample standard deviation for the two groups are given below.   Group N x̄ s Skilled 16 4.2 0.6 Novice 16 3.2 0.8   Conduct the test. Provide your significance test formula, test statistic, p-value, and degrees of freedom if applicable. What do you conclude at  σ = 0.01?

Solve only the part a, b and c for question 10.

The General Social Survey (GSS) collects data on demographics, eduction and work, among many other characteristics of US residents. Suppose we want to estimate the difference between the average number of hours worked by all Americans with a college degree and those without a college degree. Is there sufficient evidence that there is a significant difference between the average number of hours worked by those Americans with a college degree vs. those Americans without a college degree? Use the following output: Welch Two Sample t-testdata:  yes and not = 3.1181, df = 1098.5, p-value = 0.001867alternative hypothesis: true difference in means is not equal to 095 percent confidence interval: 1.011652 4.445822sample estimates:mean of x mean of y  42.81574  40.08701 Using the provided output, find the 95% confidence interval for the difference of the average amount of hours worked for those that have a college degree vs. those that do not have a college degree (ie: for the difference of two…