Data from Calvin College 2004 Seniors
This graph is a data visualization of four types of data from 271 Calvin College seniors in 2004: SAT Math score, SAT Verbal score, ACT score, and college GPA. In this graph I plotted the SAT Math score versus the SAT Verbal score with the color representing the students GPA and the radius of the circle representing the students ACT score scaled by 1/6. I have a margin of 40 pixels on the left and bottom to include the axes and labels for the graph. The scatterplot itself is scaled to 420 X 420 pixels with each tick mark being 70 pixels in length. I choose the GPA color gradients of dark blue for GPA above 3.5 with darker gradients nearer 4.0. Likewise cyan for GPA between 3.0 and 3.5, green for GPA between 2.5 and 3, yellow for GPA between 2.0 and 2.5, and red for GPA between 1.5 and 2.0. Darker gradients of the each color represent GPA nearer the upper bound for the interval.
The positioning of each point is dependent on the scales for the graph, margins, the data itself and whether we want to combine the SAT scores or not. The radius of each point can be dependent on the ACT score (scaled by 1/6 in order to fit better on the plot) or scaled uniformly. The color scale is set to be out of a 4.0 GPA scale. The axes tick labels and axes labels can be changed for each graph along with the position of the legend. This visualization does a decent job of showing the relation between SAT Math scores, SAT Verbal Scores, and the student's college GPA but it fails to demonstrate, visually, any relation of this data with the ACT score since it's hard to compare the radius of two points.
This scatterplot is similar to the one above with two changes. One, I plotted the Combined SAT score of each student versus their ACT score since it naturally makes more sense to compare a combined SAT score with an ACT score. Second, all points are uniform in size and do not represent any type of data. The color scale for GPA remains the same as above, as do the other features with exception of the axes labbels and axes tick labels which are changed to match the data plotted.
My reason for removing the radius size as a way to represent data was that it didn't seem to convey any meaninful information about an individual student nor a relation with another student. The first graph demonstrates a somewhat linear relation between a student's performance on the math portion of the SAT in relation to the Verbal portion of the SAT and shows that those with higher SAT scores, in general had a higher GPA in college. But in the second graph we see an even more distinct linear trend in the relation between the SAT combined score and the ACT score. We still see that those with higher SAT and ACT scores, in general, had a higher GPA in college. An idea to improve this further would be to have events that just show points in a specific GPA range or all points above a specific ACT or SAT score so that the graphs don't look as crowded and so that the user can narrow down the information.