Week 3 Practice with Data For each question provide your Stata code, Stata output, and respond to all questions

Week 3 Practice with Data

For each question provide your Stata code, Stata output, and respond to all questions. 

1.  Body weight (kg) measurements from a group of 11 males with heart disease and 10 males without heart disease are taken at a particular hospital.  Assume that the diagnosis of heart disease is made independently of body weight measurement.  With the summary statistics for body weight below, use the Stata calculator, and a 0.05 significance level, to test for a significant difference in mean body weight between the diseased and normal groups.  Assume that body weight is normally distributed and the variances are equal. 

a)  According to the p-value from your results from Stata, do you reject or fail to reject the null hypothesis?  Explain why. 

b)  In a complete sentence, state your conclusions regarding body weight differences in the two groups.

2.  Ten patients with advanced kidney complications were treated with the drug captopril over an 8 week period. Urinary protein (g/day) was measured before and after drug therapy, with results in the file PROTEIN.  Using Stata, test whether mean urinary protein has changed over the 8-week period. Assume the protein measurement is normally distributed and use a significance level of 0.05.  Note: You do not need to generate an additional variable to conduct this test. 

a)  Based on the resulting p-value do you reject or fail to reject the null hypothesis?  Explain why.

b)  In a complete sentence, state conclusions regarding differences in proteins over time in this study.

3.  Blood levels of lead (variable ld73, in mg/100 ml) were measured in a group of children who lived near a lead smelter in El Paso, Texas, and are found in the file called LEAD.DAT.  Forty-six children are in an exposed group (variable Group = 2) and 78 children are in a control group (variable Group = 1).  Using Stata, assess if there is a significant difference in the mean lead levels in the exposed and control groups.  Assume unequal variances, normality of the lead levels, and use a significance level of 0.05. 

a)  Based on the resulting confidence interval of the difference in means, do you reject or fail to reject the null hypothesis?  Explain why.