Assignment 12 – STAT 110 May 2012 (50 points)

1 – WSU Student Survey Data: Alcohol Consumption and Gender

Research Question: I have believe that WSU male students will have more alcoholic drinks on average than WSU female students on night in which they do consume alcohol. Is there evidence to support my hypothesis?

Use the results of the WSU student survey to test my research hypothesis.

a) The variables you need to use in your analysis are Gender and Howmuch. Classify each variable according to its data type and identify which variable is the response and which is the predictor. (2 pts.)

b) Set up the null and alternative hypothesis for answering the research question. (2pts.)

Ho:

Ha:

c) Conduct an appropriate analysis in JMP and copy and paste the results below. Comment on the assumptions required for the analysis you used and whether they are met. (3 pts.)

d) Use your results to answer the research question. State your conclusion in words.

(2 pts.)

e) Interpret the 95% CI for the difference in the means. (3 pts.)

2 – WSU Student Survey Data: Declared Major and GPA

Research Question: I have believe that WSU students that have a declared major will have higher GPA’s on average than WSU students who do not have a declared major. Is there evidence to support my hypothesis?

Use the results of the WSU student survey to test my research hypothesis.

a) Set up the null and alternative hypothesis for answering the research question. (2pts.)

Ho:

Ha:

b) Compute the estimate of the common population variance (2 pts.)

c) Conduct an appropriate analysis in JMP and copy and paste the results below. Comment on the assumptions required for the analysis you used and whether they are met. (3 pts.)

d) Use your results to answer the research question. State your conclusion in words.

(3 pts.)

e) Interpret the 95% CI for the difference in the means. What does your interval suggest about the practical signficance of the difference in the mean GPA’s? (3 pts.)

3 – Comparisons of the Mean Infant Birth Weight for Different Populations of Mothers in North Carolina Data File: NC Birth 4.JMP
In this problem you will use comparative methods to compare the actual mean birth weights of different populations of mothers. The results of your comparisons will be contained in the table below. For each situation be sure to check assumptions and briefly summarize your findings in that regard.

Use appropriate statistical methods to make comparisons of mean birth weight (in ounces or grams, your choice) across the two populations defined by the variables below:

  • Sex of child (M = male, F = female)
  • Marital status (M = married, U = not married)
  • White? (W = White vs. NW = Non-white)
  • Vaginal Delivery? (Y = yes vs. N = no)
  • Smoked? (Y = yes vs. N = no)

To organize the summary statistics, test results and CI’s enter them into the table below. For the p-value and CI columns you will need to enter the p-value from the appropriate test for comparing the two population means for each factor and the confidence interval for the difference in those population means, thus for each factor you will only have one p-value and confidence interval.

Research Question: Is there evidence that the mean infant birth weight differs across the two populations defined by the demographic variable of interest?

Factor / Sample
Size (n) / Sample
Mean / Sample
SD / p- value / CI for Difference in
Population Means
Sex of Child
Male
Female
Marital Status
Married
Not Married
White?
Non-white
White
Vaginal Delivery?
Yes
No
Smoking Status
Smoker
Non-smoker

Completed Table (10 pts.)

Summarize the results for each comparison below: (3 pts. each)

a) Sex of Child

b) Mother’s Marital Status

c) Race

d) Vaginal Delivery?

e) Smoking Status During Pregnancy

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