You will submit your homework as an R Markdown (.Rmd) file by committing to your git repository and pushing to GitLab. We will knit this file to produce the .html output file (you do not need to submit the .html, but you should make sure that it can be produced successfully).

We will review both your .Rmd file and the .html file. To receive full credit:

Create a new folder called HW8 in your repository. Use exactly this spelling with upper case letters. You can do this in the RStudio IDE, with R’s dir.create function, or using a shell.

In this folder, create a new Rmarkdown file called hw8.Rmd. Again use exactly this spelling. RStudio will give you a template, or you can use the one available here. Commit your new file to your repository. (If you are using git in a shell you will need to use git add before git commit).

In this file present your answers to the following problems. Your presentation should follow the pattern and guidelines in the class template file.

1. Abrasion Loss in Rubber Samples

Data was collected in an experiment to investigate how the resistance of rubber to abrasion is affected by the hardness of the rubber and its tensile strength. For each of 30 rubber samples the hardness and tensile strength were measured, the sample was subjected to an abrasion test, and the amount of rubber lost was recorded.

The data can be read with


The variables are hardness (in degree Shore), tensile.strength (in kg per square meter), and abrasion.loss (in in gram per hour).

2. Arrival and Departure Delays

This problem uses the New York City 2013 flights data to explore how arrival delay at the destination is related to departure delay. It provides some practice in creating useful scatter plots for a large data set.

3. Wind Speed, Time of Day, and Departure Delays

This problem again uses the New York City 2013 flights data.

The weather table provides hourly weather data for the three NYC airports for the year 2013. In this question you will look at the relationship between wind speed, time of day, and departure delays.

Create an HTML File and Commit Your Work

You can create an HTML file in RStudio using the Knit tab on the editor window. You can also use the R command


with your working directory set to HW8.

Commit your changes to your hw8.Rmd file to your local git repository. You do not heed to commit your HTML file.

Submit your work by pushing your local repository changes to your remote repository on the UI GitLab site. After doing this, it is a good idea to check your repository on the UI GitLab site to make sure everything has been submitted successfully