We have just finished another semester, and before my mind completely turns to rubble, I want to share what I believe to be a fairly good assignment. What I present below was parts of two separate assignments that I gave this semester, but upon reflection I think it would be better as one.
Read the article Let’s Practice What We Preach: Turning Tables into Graphs (full reference given below). In this article, Gelman, Pascarica, & Dodhia suggest that presentations of results using graphs are more effective than results presented in tables.
Gelman, A., Pasarica, C., & Dodhia, R. (2002). Let’s practice what we preach: Turning tables into graphs. The American Statistician, 56(2), 121–130.
Find an article in a journal that presents results (or data) in a table. Re-create the data in a tabular format using R (or Excel).
Use the functions in ggplot2 to produce a plot that conveys the same message as the original table.
Include the original table (this can be a screenshot or web-link) and citation, along with your plot.
Write a few sentences describing why the plot you produced provides a better presentation of the results or data (be sure to use recommendations from the article in making your case).
In the second part of this assignment, you will write a tutorial for the process you followed for turning a table into a plot using R Markdown and will publish that tutorial on RPubs.
There are several resources for learning R Markdown.
RStudio’s [documentation] for writing a document with R Markdown
Yihue’s [screencast] introducing R Markdown
An [example/tutorial] from PSU
Your tutorial should be written so that a student who was just learning ggplot could follow your directions easily. Include instructions for obtaining the data, getting it into a useable tabular format, manipulating the data so it can be used with ggplot, and well-commented instructions for creating your final plot. (Think of the level of detail you would want in a tutorial when you were first learning ggplot!)
It should also include:
a citation or link to the website/journal that published the original table
a view of your final data (full or a subset depending on size)
all commands necessary to create your final plot (with appropriate explanation), and
the final plot
When you knit the .Rmd document it should compile without errors.
Students commented that they learned a lot about the use of ggplot during the initial assignment (this was the second assignment in the course). The Markdown part of the assignment I gave as an extra credit assignment at the end of the class, but in retrospect, I should have made it required and done it very early on.
Here are a couple of the tutorials that I have received so far:
These students took a table of characteristics of survey participants published in the _Journal of Ethnic and Cultural Diversity in Social Work_ and turned it into a bar graph. http://rpubs.com/TSK_2012⁄3184
These students took data about trends and topics discussed in Seventeen Magazine’s Traumarama articles from 1994-2007 and turned it into a line plot. http://rpubs.com/opalc123/3155
These students took a table of data related to approval ratings and turned them into a box-and-whiskers plot. http://www.rpubs.com/GeorgeBrisse/3217
These students’ work depict a great example of how data initially presented in a table is much easier to process in a graph. The data, from a table published in the Journal of Deaf Studies and Deaf Education, show the academic status and progress of deaf and hard-of-hearing students in general education classrooms. http://rpubs.com/mens0055/3211
These students used a stacked bar chart to show data about the sample sizes for different stages for 12 problem behaviors published in Health Psychology. http://rpubs.com/nikedenise/3256
These students created a line graph representing pre- and post-training scores for consonant, vowel, sentence, and gender perception scores in cochlear implant users to examine whether an auditory training program improves performance. http://rpubs.com/koern030/3255