NSG 322 BioStatistics Week 2 – Week 3
14 + 8 Answers and calculations as basic statistics student would explain put into both an MS Excel spreadsheet and copied into MS Word doc format. Due by 7pm 2/2/14.
Week 2 Assignment
- A. What is the probability of rolling a four in the gambling dice game of craps (given two six sided dice)?
B. What is the probability that a player can roll a four 3 times in a row (assume that rolling the dice each time does not affect the outcome of the next roll)?
- Population A and Population B both have a mean height of 70.0 inches with an SD of 6.0. A random sample of 30 people is picked from population A, and random sample of 50 people is selected from Population B. Which sample mean will probably yield a more accurate estimate of its population mean? Why?
3. Suppose we obtained data on vein size after application of a nitroglycerin ointment in a sample of 50 patients. The mean vein size is found to be 7.8mm with an SD of 2.1. Using a tdistribution table, what are the confidence limits for a 95% confidence interval? For a 99% confidence interval?
4. In a pilot study evaluating the use of a new drug to lower resting heart rates (HR) of patients, the following data was recorded:
|
Subject # |
Resting HR |
|
|
001 |
72 |
|
|
002 |
88 |
|
|
003 |
71 |
|
|
004 |
87 |
|
|
005 |
64 |
|
|
006 |
77 |
|
|
007 |
79 |
|
|
008 |
59 |
|
|
009 |
66 |
|
|
010 |
68 |
|
|
011 |
78 |
|
|
012 |
89 |
|
|
013 |
91 |
|
|
014 |
81 |
|
|
015 |
77 |
|
|
016 |
75 |
|
|
017 |
69 |
|
Given that the average resting HR of the general population for this study is 72, use StatCrunch to perform the appropriate t test. What is the value of t? Using an alpha of 0.05, is the tstatistic significant? Why? What are the confidence limits for a 95% confidence interval here and what do they mean for this patient group? Copy and Paste your work from StatCrunch into your Word document submission.
5. Write one or two sentences that could be used to report the results obtained for the t-test in Exercise 4.
6. For which of the following situations is the independent groups t-test appropriate (if inappropriate, why?):
a. The independent variable is infant birth weight at one week (normal vs high); the dependent variable is resting heart rate.
b. The independent variable is radiation treatment on throat cancer patients (after a low dose and then a high dose treatment); the dependent variable is white blood cell count.
c. The IV is infant birth weight (low vs normal birth weight); the DV is number of days absent from school in first grade.
d. The IV is gender (male vs female); the DV is compliance vs noncompliance with a medication regimen.
e. The independent variable is married status (single vs divorced vs married); the dependent variable is happiness measured on a scale from 1 to 50
7. For which of the following situations is the dependent groups t-test appropriate (if not appropriate, why?)
a. The IV is presence or absence of conversation directed to comatose patients (same patients with and without conversation); the DV is the patients’ intracranial pressure.
b. The IV is birth type (home vs hospital); the DV is perceived functional ability of the patient 48 hours after surgery.
c. The IV is time since incarceration (1 months vs 3 months vs 6 months); the DV is body weight.
d. The IV is menopausal state (pre vs post); the DV is attitudes toward menopause.
e. The IV is nap therapy for narcoleptics (same patients before vs after treatment); the DV is the type of nap they had the following week (had unplanned vs didn’t have unplanned nap).
8. Suppose we wanted to test the hypothesis that a control group of cancer patients (Group 1) would report higher mean pain ratings than an experimental group receiving special massage treatments (Group 2). Use the following information. Compute a t-statistic for independent groups:
mean group 1 = 78.1 SD21 = 42.1 n1 = 25
mean group 2 = 75.1 SD22 = 39.7 n2=25
What are the degrees of freedom and the value of t ? Using α=0.05 for a two-tailed test, is this t statistic significant? Show your calculations (or StatCrunch output) for full credit.
9. Write one or two sentences that could be used to report the results obtained for the t-test in Exercise 8.
10. For each of the following t values, indicate whether the t is statistically significant for a two-tailed test, at the specified alphas:
