Stat 200 Sections 4 6 ACTIVITY SET 6 To be turned in Thursday Feb 9 Activity 6 1 Use the dataset Spring 2005 Project 1 Data that can be found in the Datasets folder of the Angel site The data are from n 690 students in Stat 200 a In the survey data set Sex in C1 gives the student s sex and Smoke in C9 gives whether the student regularly smokes cigarettes Use Stat Tables CrossTabulation and Chi Square to fill in this two way table with row percents Smoke Sex No Yes Female Male b On the basis of the row percents found in part a explain whether you think that the two variables are related c Write null and alternative hypotheses for the two variables in this activity Sex and Smoke d Use Stat Tables CrossTabulation and Chi Square click the button for Chi Square and check that you want a chi square analysis but don t check anything else in that dialog box What are the p values for the two different versions of the chi square test done by Minitab Is the result statistically significant Explain why or why not e Write a sentence than gives a conclusion about relationship or lack of relationship between the two variables in the population of college students represented by this sample Activity 6 2 Continue to use the same dataset a Use Graph Histogram to draw a histogram of the variable Study which is the student s response to how many hours per week they study What is the general shape of the histogram symmetric bellshaped skewed to the right skewed to the left b Use Stat Basic Statistics Display Descriptive Statistics to get descriptive statistics for the variable Study What is the value of the mean What is the value of the median c Give a reason why the value of the mean is greater than the median in this situation d Give the numerical value that completes the following sentence About 25 of the students said they study less than hours per week e Give the numerical value that completes the following sentence About 25 of the students said they study more than hours per week f What is the value of the IQR for hours of study per week Activity 6 3 Using the same dataset that we ve been using Spring 2005 Project 1 Data the following two way table can be created It shows the relationship between Sex and DrnksPerOcc which is student response to How many drinks do you typically have at a social occasion Counts and percentages are given for each sex separately in the following table Rows Sex Female Male Columns DrnksPerOcc 0 1or2 Count 38 66 Percent 10 03 17 41 Count Percent 31 10 06 27 8 77 3or4 97 25 59 30 9 74 5or6 110 29 02 7or8 49 12 93 9 or more 19 5 01 67 21 75 70 22 73 83 26 95 All 379 100 00 308 100 00 a What percentage of the females typically has 7 or more drinks at a social occasion Note this includes 7 or 8 and 9 or more b What percentage of the males typically has 7 or more drinks at a social occasion c Recall that the margin of error for a sample percentage is calculated as 1 n 100 Calculate the margin of error for females and separately calculate the margin of error for males d For each sex separately calculate an interval that is likely to capture the true population percentage that has 7 or more drinks at a social occasion e On the basis of the two intervals calculated in part d is it reasonable to conclude that males are more likely than females to have 7 or more drinks at a social occasion Explain f Calculate the relative risk of having 7 or more drinks at a social occasion for males compare to females g Calculate the odds ratio that compares the odds of having 7 or more drinks at a social occasion for males compared to females Activity 6 4 a Use Stat Regression Fitted Line Plot Enter GPA as the y variable and MissClass as x variable GPA is student s GPA and MissClass is the number of classes the student says he or she misses per week Describe what the plot shows about relationship between the two variables For instance is the relationship generally linear is there a positive or negative association does it look like a strong or a weak relationship are there any outliers b Write the regression equation determined by Minitab It will appear at the top of the plot found in part a You can round off the slope if you wish c Refer to the previous part What is the value of the slope of the regression line Write a sentence that interprets this slope in the context of these variables d Use the equation found in the previous part to predict the value of GPA for a student who misses 2 classes per week e Calculate the value of a residual for an observation that has the values MissClass 2 GPA 3 3 Note that the value of MissClass is the same as in part d f Use Stat Basic Statistics Correlation to find the correlation between MissClass and GPA What is the value Does the value indicate a weak or a strong relationship A positive or a negative association