A (Not So) Quick Word About Recall Bias

I was reading through some of the reviews of a restaurant the other day when I read some comments by several people who swore that they had been made sick by food from that restaurant. One commenter stated that they had become “gravely ill” soon after leaving the restaurant. Another commenter agreed, saying that they had become ill “about a half hour” after eating at the same establishment. Soon after that, others piled on. As I watched the ratings site, I was very upset to see what became a comedy of stupidity hours later.

Judging by the comments, the incubation time for their disease was between 30 minutes and TWO WEEKS. Not only that, but their onsets were days and weeks apart from each other. This leads me to one of two possible conclusions: 1) The restaurant has an enormous problem with regards to hygiene to the point that they are making people sick on a prolonged scale spanning weeks. Or 2) the commenters were exhibiting – at the very least – recall bias and/or – at the very worst –  a mob mentality.

Then again, they could all have been the same person with some sort of vendetta. (I’m not linking or publishing the exact quotes because the restaurant already has enough issues.)

It is very natural for us to associate our illness to the very last thing we ate before we got sick, especially if we are not familiar with things like “incubation times” or the modes by which viruses and bacteria that we eat can make us sick. For example, Norovirus takes just a few viral particles to make a person sick. The incubation time – the time from infection to symptoms – ranges from 24 to 48 hours with Norovirus, certainly not 30 minutes. That is, you’re completely symptom free for about a day before you get really sick form Norovirus.

Salmonella and E. coli make you sick through the cunning use of toxins. Alright, alright… They don’t do it on purpose. It’s just that some of their metabolic byproducts of their own cell membrane may act as a toxin once in our gut. Their incubation times? 12 to 72 hours for Salmonella and 3 to 4 days for E. coli. Again, no where near the 30 minute mark. And certainly not two weeks later.

What could cause disease in 30 minutes or less or your money back?

Staphylococcus aureus or Bacillus cereus can make you sick in 30 minutes after ingesting their toxins… But it’s a stretch in this case, especially in light of others reporting such disparate incubation times.

This is why it is necessary for health departments and health care providers to educate the public on the nature and behavior of gastrointestinal disease – and other diseases as well. Because that lack of understanding can not only lead to a restaurant or other food businesses to be wrongly accused of making people sick – which can have them go under financially – it can also muddy up investigations of serious food borne outbreaks.

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2 thoughts on “A (Not So) Quick Word About Recall Bias

  1. Ha! That would be great. Then the people will accuse me of a conflict of interest by being paid by the restaurant. Arguing with some people just isn't worth the time nor the money.

  2. This restaurant needs to put your post up on their front door and hire you as a consultant. I was just thinking about this same issue the other day in terms of vaccines (what a shock!). Great example of how we like to attribute meaning to things temporally, when in reality there is no association at all.

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