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.

The largest group that has other dementias, the biggest grey box on the left, smokes no cigarettes.

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

One group that has more cases than expected given independence, is the other dementias box. It is one of the larger boxes and its purple due to smoking over 20 cigarettes per day.

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

According to the masaic chart, smoking doesn’t seem to matter in determining other dementais. The largest block in the other dementias row falls under the none column, therefore the largest population of other dementias don’t even smoke.

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).

The four varibles that have a negative correlation with the number of trail users are: Spring, Fall, Precipitation and Cloud Cover.

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

Fall seems to be the least popular season for trail users.

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. Although it’s hard to say that there is no correlation for certain since that value is not 0, I beleive it’s okay to assume there in no correlation since it sits at a miniscule .1.

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.

Yes, after examining the scatter plot, it’s easy to conclude that the two variables have no ccorrelation due to the fact that the points are scattered sparatically all over the graph.

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.