Statistics homework help
Statistics homework help. 226 Bonus Review 3 – Chapters 9-12
For each of the following problems (except the questions that simply ask you to fill in the tables), conduct the appropriate hypothesis test or construct the appropriate confidence interval. In addition, for each word problem, conclude with a sentence that explains what the results MEAN.
1a. Tanya knows that fiber is important for digestive health. Therefore, she thinks that people who take fiber pills daily will have fewer stomach aches. To test this, Tanya asks 64 participants to take a fiber pill each day for one month and to record how many stomach aches they suffer in the following month. Tanya knows that people who don’t take fiber pills daily generally suffer about 2 stomach aches per month, on average. If Tanya’s sample suffers 1.8 stomach aches per month, on average, with a standard deviation of 2.1, can Tanya conclude that taking fiber pills daily will result in significantly fewer stomach aches?
1b. Construct the two-tailed 90% Confidence Interval that estimates the true population average number of stomach aches suffered in one month by people who take fiber pills daily. Make sure to include a concluding statement explaining the meaning of what you calculated.
2. Adrian conducts an independent-measures ANOVA analysis where k=4 and n=10. Fill in the table below.
SS Df MS F
Between
Within 3
Total 126
3a. Tanya determines that she cannot rely on the average in the general population being 2 stomach aches per month. Therefore, she decides to take a different approach. Tanya splits her 64 participants into two groups – one group of 32 participants takes a fiber pill daily and the other group of 32 participants takes a placebo pill daily instead. If the fiber group reports an average of 1.7 stomach aches per month, with standard deviation 0.5, and the placebo group reports an average of 1.9 stomach aches per month, with standard deviation 0.8, can Tanya conclude that taking fiber pills daily results in significantly fewer stomach aches?
3b. Construct the two-tailed 99% Confidence Interval that estimates the true population mean difference between the fiber group and the placebo group. Make sure to include a concluding statement explaining the meaning of what you calculated.
4a. Tanya could have chosen another way to investigate her research question. If Tanya had used only a sample with n = 32, she might have decided to test each person before and after they take fiber pills in order to determine whether the number of stomach aches went down, on average, after people took fiber pills daily for one month. Therefore, in this case, Tanya decides to follow her 32 participants for 3 months. In the first month, Tanya asks participants to record the number of stomach aches they have. In the second month, Tanya instructs her participants to simply take a fiber pill each day. In the third month, Tanya again asks participants to record the number of stomach aches they have. Tanya finds that the mean number of stomach aches goes down from the first to the third month, and calculates MD = -0.4 and sD = 0.1. Does taking fiber pills daily significantly decrease the number of stomach aches suffered in a month?
4b. Construct the two-tailed 95% Confidence Interval that estimates the true population mean of the difference scores between number of stomach aches suffered in the first month vs. the third month. Make sure to include a concluding statement explaining the meaning of what you calculated.
5. Tanya then decides to ask a slightly more complicated question. In addition to looking into whether fiber pills have any effect on stomach aches, she decides to look into whether placebo pills have any effect on stomach aches too. Therefore, she recruits 45 participants for her study and divides them into three groups. The first group takes no pill for a month and then records how many stomach aches they suffer in the following month. The second group takes a placebo pill every day for a month and then records how many stomach aches they suffer in the following month. The third group takes a fiber pill every day for a month and then records how many stomach aches they suffer in the following month. The data follows. What can Tanya conclude?
No pill Placebo pill Fiber pill
M=2.4, s=0.8, n=15 M=2.3, s=0.4, n=15 M=1.9, s=0.5, n=15
6a. Tanya then tries to replicate her study and recruits another 45 participants to run the same study as in the question above. For her replication, she finds that the mean for her “no pill” group is 2.2, the mean for her “placebo pill” group is 2.0 and the mean for her “fiber pill” group is 2.1. Fill in the table below.
SS Df MS F
Between 10 1.67
Within
Total
6b. Do Tanya’s results from her replication experiment agree with the results from her original experiment (i.e., compare your results for questions 5 and 6a)? Explain.
7. Betty wants to know if eating chocolate makes people laugh more. To that end, she designs a study where people are divided into three groups – one group eats no chocolate, one group eats a bit of chocolate and one group eats a lot of chocolate. Betty recruits 15 people for her study and randomly assigns each person to one of the three groups. The 15 people spend a week in their respective groups and then all people are shown the same comedic video. Betty records how much time each person spends laughing. The data follows. (HINT: we used this question in the bonus review for exam 1 so you probably already have some things computed.)
No chocolate Bit of chocolate Lots of chocolate
20 seconds
30 seconds
25 seconds
10 seconds
14 seconds 30 seconds
28 seconds
15 seconds
29 seconds
33 seconds 45 seconds
48 seconds
47 seconds
60 seconds
80 seconds
Does eating chocolate make people laugh significantly more? (i.e., what can Betty conclude?)
8a. Virginia thinks that tutoring improves students’ grades. To test this, she recruits a sample of 10 students and notes their grades on their first exam of the semester. She then sends the 10 students to a tutor for one hour per week for the remainder of the semester. Finally, she notes these same 10 students’ grades on the final exam of the semester. Based on the data below, is Virginia right? (i.e., does tutoring significantly improve student grades?)
First Exam Final Exam
85
75
78
68
90
85
68
82
73
70 88
77
77
70
93
86
69
84
71
72
8b. Based on your conclusion above, would the two-tailed 90% Confidence Interval estimating the true population mean grade difference between the first and final exams include 0 or not?
9a. Paul thinks that giving students an extra hour to take a test will affect their performance on the test. To test this, he recruits a sample of 10 students and gives them 3 hours to take a test that people usually take in 2 hours. If Paul’s sample scores an average of 78 with standard deviation 3, and the general population usually scores an average of 80 (when taking the test in two hours), can Paul conclude that giving students an extra hour to take a test significantly affects their performance on the test?
9b. Based on your conclusion above, would the two- tailed 95% Confidence Interval estimating the true population average score for all people if they had 3 hours to take the test include 80 or not?
Talk to us support@bestqualitywriters.com