Q1

Your task in this question is to fit a simple linear regression of y on x to four datasets and examine residual plots to determine the adequacy of the simple linear regression model. Three of the four datasets have at least one problem. For these three, state what the problem is and give one plot that displays the problem. For the dataset that has no problems, write a statistical summary interpreting your estimates of the slope and intercept.

The four datasets are called df1, df2, df3 and df4 and you can load them with

load(url("http://stat512.cwick.co.nz/data/df1.rda"))
load(url("http://stat512.cwick.co.nz/data/df2.rda"))
load(url("http://stat512.cwick.co.nz/data/df3.rda"))
load(url("http://stat512.cwick.co.nz/data/df4.rda"))

Q2

Find a news article (blogs on news sites are o.k.) reporting the results of a scientific study.

1. Provide a link to the article and provide the headline of the article in full.

2. Does the article’s headline imply a cause and effect relationship and/or a generalization to a population larger than that studied?

3. Do you think the headline was an accurate portrayal of the inferences supported by the study? Justify your answer.

Some examples of headlines I found:

• “Eating nuts in pregnancy tied to lower allergy risk in offspring”
• “Dogs poop in alignment with Earth’s magnetic field”
• “Barefoot Running Can Cause Injuries, Too”

Still having problems identifying causal language? You might find this article helpful.