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 smokes 0 cigarettes a day.

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

There were more cases than expected in other dementias where the person smokes more than 20 cigarettes per day.

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

I believe smoking is more of a confounding variable and the correlation is based off of other sets of variables as the spread of cases in all of the diseases has a similar pattern with cigarettes per day.

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).

Spring, Fall, Cloud Cover and Precipitation all of negative correlation with volume.

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

Fall is the least popular with a -0.25 correlation.

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

No, I actually believe that they are related based off of Cloud Cover’s correlation with Low Temp being a particularly positive one.

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?

As there is no way to draw a line of best fit to match this set of data, I would conclude that the data does not prove that the variables are related, however looking at the bottom right hand of the plot is the highest concentration of low high temperatures and high cloud coverage.

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

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

Q10 Use the correct slug.