Tufte criticizes Boeing report on Columbia foam impact

[Keith Soltys <keith -at- soltys -dot- ca>]

In light of the recent discussions of Edward Tufte's criticisms of the 
way bad data presentation contributed to the Challenger disaster, I 
thought that this might be relevant:

http://www.edwardtufte.com/714883858/bboard/q-and-a-fetch-msg?usca_p=t&msg_id=0000Rs&topic_id=1

On this page he critiques the slides used by Boeing to assess the damage 
caused to Columbia by the foam strike.

Much of the criticism is in the form of jpeg images, but here's a plain 
text excerpt from the page:

"The 3 reports have the following weaknesses: It now appears that the 
conclusions were incorrect. The results appear sensitive to input 
assumptions about incidence angle, incidence location, the number and 
velocity of impacts, and the weight of the debris (assumed to be 
lightweight foam at 2.4 pounds/cubic foot)--and that multivariate 
sensitivity is not carefully examined. In the video of the debris 
impact, the debris pieces look larger than the estimated sizes (20" by 
10" by 6"; and 20" by 16" by 6") used in the 3 reports. The important 
video is at http://www.spaceref.com/Columbia/post.launch.video.html The 
video also shows a fine shower of debris coming off the wing after 
impact; that spray does not immediately suggest foam chips. In the 
reports, assumptions tend to be evaluated generally in the direction of 
how they might reduce the seriousness of the threat (after-the fact 
arguments of the form "this is a conservative estimate" replace careful 
quantitative estimates of robustness and uncertainty). An important 
table has 2 empty cells; threat assessments are missing in those 2 
cells. The good diagram showing forecasted tile loss provides only point 
estimates; there is no cloud of error around those estimates.

The 3 reports have the following analytical design characteristics: They 
appear to be PowerPoint slides. Some tables are difficult to read 
because of the grid prisons surrounding the entries in the spreadsheet, 
and it is difficult to make comparisons of numbers across the table. 
Bullets lists are used throughout, with up to 5 levels of hierarchy on a 
single page of 10 or 12 lines. Consequently the reasoning is broken up 
into stupefying fragments both within and between the many slides."

Definitely worth looking at if you are interested in how bad 
communication can have real-world consequences.

Regards
Keith


--
Keith Soltys
Email: keith -at- soltys -dot- ca - Alternate Email: ksoltys -at- rogers -dot- com
Web: http://www.soltys.ca
Home of Internet Resources For Technical Communicators



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