(This article was originally published at Junk Charts, and syndicated at StatsBlogs.)
This chart is in the Sept/Oct edition of Harvard Magazine:
Pretty standard fare. It even is Tufte-sque in the sparing use of axes, labels, and other non-data-ink.
Does it bug you how much work you need to do to understand this chart?
Here is the junkchart version:
In the accompanying article, the journalist declared that student progress on NAEP tests came to a virtual standstill, and this version highlights the drop in performance between the two periods, as measured by these "gain scores."
The clarity is achieved through proximity as well as slopes.
The column chart form has a number of deficiencies when used to illustrate this data. It requires too many colors. It induces involuntary head-shaking.
Most unforgivingly, it leaves us with a puzzle: does the absence of a column means no progress or unknown?
PS. The inclusion of 2009 on both time periods is probably an editorial oversight.
Please comment on the article here: Junk Charts
