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 dimentias are people that do not smoke cigarettes. This is shown by the largest bar on the mosaic smoking chart for the other dimentias category.

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 are people that have other dimetia and also smoke more than 20 cigarettes per day. This is shown by the blue color on the mosaic smoking graph.

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

No, smoking does not seem to matter in determining other dimentias. People who smoke any amount of cigarettes have a similar amount of cases for dimentia compared to those who do not smoke at all.

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, cloud cover, precipitaion, and spring all have negative correlation with the number of trail users.

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

Fall seems to be the least popular season for trail users. This is shown on the chart by a number of -0.25 for volume during the fall.

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.

No. There could be a correlation between the two variables, although it would be a non-linear correlation.

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.

This scatter plot shows that the variables hightemp and cloudcover are not related at all.

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.