In official statistics we’re used to dealing with highly aggregated data. To visualise those, bar-, line- and pie charts are standard tools. But there is a whole other side to visualisation where it is used to recognize patterns, outliers or errors in individual data.
In the above excerpt of the daily flight data for 1995–2008 (click image to see all the years covered) the effect of 9-11 is the most obvious, where flight activity stopped completely and had a hard time to recover for several months.
But there is so much more information in there:
- the weekly pattern: less flights on weekends
- the seasonal pattern: most flights in July and August
- the 9-11 pattern: few flights on 9-11-2002
You can watch Mike Bostock live at W3Conf: Practical Standards for Web Professionals on November 16th, 2011 or later as a video download.