Thursday, February 1, 2018

When did we become gluten intolerant?

I don't know about you all, but I've been doing this since the early 2000s.

The dynamic information equilibrium approach I talk about in my recent paper doesn't just apply to economic data. The idea that the information content of observing one event relative to observing another event has rather general application. As an example, I will look at search term frequency. Now if the English language was unchanging, given that there are a huge number of speakers, we'd expect relative word frequencies to remain constant and the distributions to be relatively stable. Changes to the language would show up as "non-equilibrium shocks" — a change in the relative frequency of use that may or may not reach a new equilibrium. A given word becomes more or less common and therefore has a different information content when a that word is observed (a "word event").

We might be able to see some of these shocks in Google trends data — a collection of "word events" entered as search terms. It's is only available since 2004, so we really can only look at language changes that happen within a few years. Longer changes (e.g. words falling into disuse) won't show up clearly, but this time series is well-suited for looking at fads.

I wanted to try this because I read an offhand comment somewhere (probably on Twitter) that said something like "everyone suddenly became gluten intolerant in 2015" [1]. What does the search data say?

The gluten transition in the US is centered near January 2009, but takes place over about 6 years (using the full width at half maximum for the shock). It "begins" in the mid-2000s and we seem to have achieved a new equilibrium over the past couple years.

How about avocado toast? That happened around 2015 in the US:

However, I did notice on Twitter there were a lot more and earlier references to avocado toast from Australians (in fact I think it was a mention in Australian media that it wasn't just the breakfast I made myself for years after having been given it by a Chilean friend where it's been a common dish for a long time ("palta")). Was this hunch visible in the data? Yes — almost a full year earlier:

So anyway, I just wanted to show a fun application of the information equilibrium framework. It applies to a lot of situations where there is some concept of balance between different things: supply and demand, words and their language, cars and the flow of traffic, neurons and the cognitive state, or electrons and information.


Update 2 February 2018

The "macro wars" (Nov 2007–Mar 2011):



[1] Update: found it.
As a casual student of American food faddism, something that is still more than alive and well today (Yes, it’s an amazing coincidence that a sizable percentage of the educated liberal upper middle class all became gluten intolerant over a 3 year period. Must be pollution or something), I always love stories about our ridiculous food history.
It's a 6-year period above, but the definition of the "width" of a transition is somewhat arbitrary (I used the full width at half maximum above).


  1. What are the tan apple sauce looking clumps atop your avocado toast (presumably from the bottle in the background)? I can't make out the label. So those are the ingredients? Toast, avocado and tan sauce?

    I think I just heard of "avocado toast" within the past four months.

    1. It is an artisanal ginger-Scotch bonnet hot sauce from Brooklyn for an added hipster touch.

      I think the traditional "avocado toast" is just avocado and toast. The palta chilena tends to come with some other protein (my friend told me jamon, but I frequently put sliced turkey that I have around for the kid's lunches).

      I don't know if you follow Cameron Murray on twitter, but he'd linked an article or two that make the rather silly claim that young people in Australia can't afford (skyrocketing) housing because they spend their money on avocado toast. Only recently did Duncan Black also poke fun at that idea (with the Brooklyn reference serving as the inspiration for the breakfast photographed above).

    2. I do follow Murray, but missed that. Thanks.

  2. I looked up "Information Transfer Economics" on Google trends... not enough data to make a graph (it said).

    1. "macro" has an interesting trend that looks like two shocks and a long run dynamic equilibrium.

    2. Personally I've encountered "macro" this past year far more frequently on Facebook butterfly enthusiast pages (in reference to "macro photography") than anywhere else.


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