Lab 4
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BE SURE TO PUT YOUR NAME, Sec # / CLASS TIME, AND THE LAB # ON YOUR SUBMISSION. BE
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ORDER. 1 POINT WILL BE CUT OFF FOR NOT DOING SO.
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Purposes:
1) Hypothesis tests for means
2) Hypothesis tests for two means
3) Hypothesis tests for paired data
For this lab, you should reference all the code we used last week in lab 3,
including the same datasets. The code is almost identical to the three sets we
did last week with this slight modification, "H0=<claim>":
SAS Learning code:
proc ttest data=one alpha=0.10 H0=100;/*Tests if the mean score is 100*/
var score;
run;
SAS Learning output (look for the bolded part):
Variable: score N Mean Std Dev Std Err Minimum Maximum 21 93.6667 13.9869 3.0522 57.0000 121.0 Mean 90% CL Mean Std Dev 90% CL Std Dev 93.6667 88.4025 98.9308 13.9869 11.1609 18.9891 DF t Value Pr > |t| 20 -­‐2.08 0.0511 Note: SAS ALWAYS produces two sided P-values, so if you are doing a one-sided test, you need to divide
the P-value SAS gives you by 2.
Problem 1
Use the data contained in the file dogs.txt, we would like to test if the true mean weight is less than 60 pounds.
Use α = 0.01.
a) State your appropriate null and alternative hypothesis.
b) Run the test in SAS and provide output showing the DF, t Value, and P-value.
c) What is the actual P-value for your test? Do you Reject H0 or Fail to Reject H0.
d) State your conclusion is layman's terms.
Reference the code from last week, remember to use the "satterthwaite"
results:
Problem 2
The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures students' study habits
and attitude toward school. Scores range from 0 to 200. Higher scores indicate better attitudes. An educational
psychologist believes that older students (group 1) have a better attitude toward school than younger students
(group 2). Use the data contained in the file ssha.txt to test the psychologist's belief. Use α = 0.10.
a) State your appropriate null and alternative hypothesis.
b) Run the test in SAS and provide output showing the DF, t Value, and P-value.
c) What is the actual P-value for your test? Do you Reject H0 or Fail to Reject H0.
d) State your conclusion is layman's terms.
Again, reference the code from last week. Also for this problem, be careful
when setting up your alternative and make sure it matches the difference you
are using (you can do it either way, female - male or male - female but then you
must follow thru accordingly):
Problem 3
Does a pretty nurse raise blood pressure? A cardiologist suspects that measurements of his male patients' blood
pressure have been artificially elevated since he hired a young, attractive nurse. To test this theory, on a
particular day, he randomly selects some male patients to have their blood pressure taken by the new female
nurse and then again a few minutes later by a male nurse.
Note: the difference in blood pressure has to be more than 5 points higher to be practically significant so this
will be our test, use the data contained in the file nurse.txt to test this practical difference. Use α = 0.05.
a) State your appropriate null and alternative hypothesis.
b) Run the test in SAS and provide output showing the DF, t Value, and P-value.
c) What is the actual P-value for your test? Do you Reject H0 or Fail to Reject H0.
d) State your conclusion is layman's terms.