homework,

Week 3 Assignment

1. Using StatCrunch, calculate the chi-square statistic and degrees of freedom for the following set of data for 300 people:

Group A Group B Group C Total

Had flu shot 20 30 32 82

Didn’t have flu shot 80 70 68 218

Total 100 100 100 300

Is the value of the chi-square statistically significant at the 0.05 level?

2. Write a paragraph summarizing the results of the analysis in Exercise 1.

3. Using StatCrunch, calculate the chi-square statistic and degrees of freedom for the following set of data for 180 people undergoing a knee replacement treatment with a drug supplement:

Treatment with drug X Treatment without Drug X Total

Had > 8 wk rehab 18 32 50

Had < 8 wk rehab 70 60 130

Total 88 92 180

Is the value of the chi-square statistically significant at the 0.05 level?

4. Write a paragraph summarizing the results of the analysis in Exercise 3.

5. Below are three sets of expected frequencies for the four cells of 2 X 2 contingency tables. Identify which statistical procedure would be appropriate for each, using the most conservative approach.

a. 4 4 b. 35 35 c. 9 9

21 21 65 65 91 91

6. For this second question - let's try to make a crosstabulation table for a problem we don't have in the textbook.

We want to know whether boys or girls get into trouble more often in school. Below is the table documenting the percentage of boys and girls who got into trouble in school:    Got in Trouble    No Trouble  Total Boys       46                   71          117 Girls        37                   83          120      Total       83                 154          237

Examine statistically whether boys got in trouble in school more often.  Can you create a StatCrunch crosstabulation table result  for this data (copied and pasted, as well as updated in Word),  and a Chi-Square analysis?  Hypotheses?  Remember to see the video on Chi-Square analysis with StatCrunch from question 1 for help with StatCrunch (and you may also find the short video on making cross-tabulation tables with summary data helpful in the instructional video link at the left.

For number one, they said a two by three groups chi square. Remove the total, and then total the 300 in the end. Input the 3 numbers in 3 column. Tell whether the got a flu shot. Put hypothesis.

For Number 5, they said it is 3 statistical approaches, chi square and another two you may know it.