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 consists of non-smokers who smoke zero 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 independence, would be smokers who smoke more than 20 cigarettes per day.

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

In determining other dimentias, smoking does not seem to matter. The mosaic chart supports this theory because it displays non-smokers, who smoke zero cigarettes per day, as the largest group.

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 a negative correlation with the number of trail users in volume include the following: spring (-0.04), fall (-0.25), cloudcover (-0.37), and precipitation (-0.23).

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

The least popular season for trail users is Fall due to it having the largest negative correlation with users in comparison to the other seasons.

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.

There is no way to be sure that there is no relationship betweeen the two, however a relationship is assumed due to the coefficient being above zero.

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.

The scatter plot indicates that the two variables are not related at all. This may be because the scatter points do not form a line or stay together whatsoever.

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.