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 Alzheimer. Discuss it by number of cigarettes per day.

The largest group that has alzheimer is the non smoking group. The no smoking category is the largest category under alheimer, and is much bigger than the other groups under alheimer.

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

The other dementias and greater than 20 is the one group that has more cses expected than given inddpendence. The number of cigarettes per day was greater than 20, and was quite a big part of the other dementias.

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

The mosiac chart shows no linear correlation between alzheimer and number of cigarettes per day. Only one category showed some kind of linear correlation.

Q4 Create correlation plot for RailTrail.

Hint: The RailTrail data set is from the mosaicData package.

Q5 What variables have positve correlation with the number of trail users (volume)?

Hightemp, avgtemp, lowtemp, and summer have a positive correlation with volume. There are other options that correlate with volume, but they are less than 0 and correlate negatively.

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

Summer seems to be the most popular season for trail users. When we look at the correlation with the volume and other seasons and find that summer has the highest positive ocrrelation with volume.

Q7 The correlation coefficient between hightemp and cloudcover is quite small. Would you be sure that the two variables are not related at all? 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 two variables have a correlation almost at zero when we look at the correlation plot. Then when we make the scatter plot, there does not appear to be any correlation between the two variables.

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.