Quiz3

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 were non-smokers, 0 cigarettes per day.

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 chance were people with other dementias who smoked more than 20 cigarettes per day.

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

After examining the plot, I can say that smoking does not matter in determining other dementias. There is only one group of people where there are more cases than expected which were people with other dementias who smoked more than 20 gigarettes per day. And the sample size is too small anyway so nothing is conclusive.

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 variables that have negative correlation with the number of trail users are Spring, Fall, Clodcover, and Precipitation.

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

The Fall seems to be least popular for the 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?

I actually do believe that these two variables are related. The more cloud cover there seems to be, the lower the hightemp will be.

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.