Quiz 3

The data set is from a case-control study of smoking and Alzheimer’s disease. The data set has two variables of main interest:

• smoking a factor with four levels “None”, “<10”, “10-20”, and “>20” (cigarettes per day)
• disease a factor with three levels “Alzheimer”, “Other dementias”, and “Other diagnoses”.

Q1 Describe the largest group that has other dementias. Discuss it by number of cigarettes per day.

People that are not smoking cigarettes has the biggest is the biggest group of people that have other dementias.

Q2 Describe one group that has more cases than expected given independence (by chance). Discuss it by number of cigarettes per day.

The people that are smoking more than 20 cigarettes that have other dimentia, which is the blue square on the chart.

Q3 Does smoking seem to matter in determining other dementias? Discuss your reason using the masaic chart above.

There is little to no relationship between smoking and other dimmentias because they are all about the same size and the the two biggest boxes are not smoking and smoking 20+ cigarettes.

Q4 Create correlation plot for RailTrail.

Hint: The RailTrail data set is from the mosaicData package.

Q5 List all four variables that have negative correlation with the number of trail users (volume).

Fall -.25, Spring -.04, Cloud Coverage -.37, and Precipitation -.23 are all the variables that have negative correlations with volume.

Q6 What season seems to be least popular for trail users?

Fall seems to be the least popular for trail users with a -.25 correlation with the volume.

Q7 The correlation coefficient between hightemp and cloudcover is quite small. Would you be sure that the two variables are not related at all?

Hint: One word answer (e.g., yes or no) is NOT enough. Explain why.

Cloud Cover and High Temp have very little to no correlation because it is a -.01 correlation and the color of the square is white sudgesting that it may has no correlation at all.

Q7.a Continued from Q7. Create scatter plot. After examing the scatter plot, would you conclude that the two variables are not related at all?

Hint: Discuss your reason by explaining your scatter plot.

Q8 Hide the messages, the code and its results on the webpage.

Hint: Use message, echo and results in the chunk options. Refer to the RMarkdown Reference Guide.

Q9 Display the title and your name correctly at the top of the webpage.

Q10 Use the correct slug.