"Envelope Graph" - SAS Global Forum 2012 Presentation
The visuals below are part of the presentation we will be making at the SAS Global Conference in April, 2012. The presentation is co-authored with Aaron Daniels and Jacob Warwick.
The visuals come from a data set of user web hits at a private school where all employees and student have laptops.
The challenge was to take recorded web hits from 8am to (by second) and create visuals that showed time and usage. The data set had fourteen million entries.
The visual below shows the internet usage by just the students (grades 6 - 12) during the school day only. The internet hits go through a router that categorizes them and so we were able to create further simplified categories below. Note that 'Bad Usage' is attempted but blocked by the router.
external image during-school1.png

The second image is student internet use after school. Note that internet use is still blocked on school computers outside of school (i.e. 'Bad Usage'), but there are less blocks placed on 'Distracting Usage'. This category includes Facebook, Twitter and so on.
external image after-school.png

Our next step is to create visuals that show exactly what the four categories are (i.e. sports, steaming, etc.) and their corresponding weighting of use in the larger categories.

Grade Inflation?
A few weeks ago I was asked: "Is there evidence of grade inflation in the school over the past five years?"
The challenge was to create a visual that administrators and college counselors could quickly understand and interpret.
Using data that had the final course grades for all courses taken by all the students in a graduating class (i.e. class of "2008", etc.), I found a mosaic plot the most effective method of presenting the data

external image gi1.png

There is clearly a trend towards and increase of A grades being given over the last five years, however to explain "why?" is trickier. Comparing standardized testing scores is probably the next step.
Whatever the cause, looks like the gentleman's C is now the gentleman's B.

The Challenge of Home Owning

The financial woes of the American middle-class are well documented and a big issue in American politics.
However, something that is less focused on is the cost of home-owning.
It is not only that median US income has struggled relative to inflation, but the cost of buying a home has greatly increased relative to income.
Explore the bubble plot below. The vertical axis is the ratio of US median house price versus US median household income. See what happens over time. Click on the bubble and it will trace its path.