Challenger: a Missed Opportunity of Statistical History or Organizational Dysfunction?

The space shuttle Challenger exploded 73 seconds after lift-off on January 28, 1986.

The cause of the disaster was traced to the failure of an O-ring seal. O-rings were used to isolate the fuel supply from burning gases.

The accident killed the seven crew members.

“We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and ‘slipped the surly bonds of earth’ to ‘touch the face of God.'”

• Ellison Onizuka
• Michael J. Smith
• Judith Resnick
• Dick Scobee
• Gregory Jarvis
• Ronald McNair
• Christa McAuliffe

… failures in communication … resulted in a decision to launch 51-L based on incomplete and sometimes misleading information, a conflict between engineering data and management judgments, and a NASA management structure that permitted internal flight safety problems to bypass key Shuttle managers.</q

Rogers Commission Report (1986)

Rogers Commission Report (at 149)

Incidents When O-Rings Failed

This is the key graph of the O-ring test data that NASA analyzed before launch. Is there any pattern between temperature and the O-ring failure rate? </q

If you were the decision maker for launch and only had this graph, would you have allowed the space shuttle to launch at 31°F, the temperature on the day of the launch?

This linear model represents the implied relationship between distressed O-rings and temperature. Cleary, there is no relationship based on data.

Displaying only the distressed O-rings was an epic-mistake.

Would this have Overcome the Seeming Failure of (Visual) Communication?

A careful analysis of the flight history of O-ring performance would have revealed the correlation of O-ring damage and low temperature.

Rogers Commission Report (at 149)

Would it had been enough?

The linear model fit over the entire data set of O-ring failures and successes would have revealed a positive relationship between Distress and Failure; perhaps

[1] "Accuracy= 87 %"

Michael Friendly, 2001

One virtue of a good graphical display is to allow us to see patterns, trends, or other structures which would otherwise be concealed in another form of display. It may be heartbreaking to find out that some important information was there, but the graph maker missed it. The story behind the Challenger Disaster is perhaps the most poignant missed opportunity in the history of statistical graphics. But such graphical failures often provide useful lessons.