11. Kahneman, Daniel. Thinking, fast and slow. Farrar, Straus and Giroux, 2011.
are often perceived to cause more deaths than asthma, while in reality
asthma causes 20 times more deaths.
In the case of Hurricane Sandy, since the median age of the U.S. pop‐
ulation is 37, the last time fuel shortages were at the top of the news
(in 1973-74 and 1979-80) was before about half of the U.S. population
was born, so it’s easy to see how most people did not think to prepare
for this eventuality. Of course, the hindsight bias makes it obvious that
such preparations were necessary.
The availability bias impacts outages and postmortems in several ways.
First, in preparing for future outages or mitigating effects of past out‐
ages, we tend to consider scenarios that appear more likely, but are, in
fact, only easier to remember either because of the attention they re‐
ceived or because they occurred recently. For instance, due to its se‐
verity, many organizations utilizing AWS vividly remember the April
21, 2011, “service disruption” mentioned previously and have taken
steps to reduce their reliance on the Elastic Block Store (EBS), the
network storage technology at the heart of the lengthy outage. While
they would have fared better during the October 22, 2012, “service
event” also involving EBS, these preparations would have done little
to reduce the impact of the December 24, 2012, outage, which affected
heavy users of the Elastic Load Balancing (ELB) service, like Netflix.
Furthermore, especially under stress, we often fall back to familiar
responses from prior outages, which is another manifestation of the
availability bias. If rebooting the server worked the last N times, we
are likely to try that again, especially if the initial troubleshooting offers
no competing narratives. In general, not recognizing the differences
between outages could actually make the situation worse.
Although much progress has been made in standardizing system
components and configurations, outages are still like snowflakes, glo‐
riously unique. Most outages are independent events, which means
that past outages have no effect on the probability of future outages.
In other words, while experience with previous outages is important,
it can only go so far.
Cognitive Biases | 17