Eating Season

Happy almost Thanksgiving! Please enjoy this bit of trivia I recently stumbled on about American food consumption patterns during this time of year! It’s from the book “Devoured: From Chicken Wings to Kale Smoothies – How What We Eat Defines Who We Are” by Sophie Egan.

From page 173:

A few paragraphs later, she goes a bit more in depth about what happens to shopping habits (note: she quotes the embattled Cornell Food and Brand lab, but since their data matches another groups data on this, I’m guessing it’s pretty solid):

I had no idea that “eating season” had gone so far outside the bounds of what I think of as the holiday season. Kinda makes you wonder if this is all just being driven by winter and the holidays are just an excuse.

On a related note, my capstone project is done/accepted with no edits and I will probably be putting up some highlights about my research in to food insecurity and health habits on Sunday.

Happy Thanksgiving!

Grade Prediction by Subject

I saw an interesting study this week that seems to play in to two different topics I’ve talked about here: self reporting bias and the Dunning-Kruger effect.

The study was “Examining the accuracy of students’ self-reported academic grades from a correlational and a discrepancy perspective: Evidence from a longitudinal study“, and it took a look at how accurate students self-reported grades were. This is not the first time someone has looked at this, but it did add two key things to the mix: non-US test scoring and different academic subjects over different years of school. The students surveyed were Swiss, and they were asked to report their most recent grade in 4 different subjects. This was then compared to their actual most recent grade. The results were pretty interesting (UR=under-report, OR=Over-report, T1-T3 are years of school):

Unsurprisingly, kids were much more likely to over-report than under-report. Since most of the differences were adding a half point or so (out of 6), one wonders if this is just a tendency to round up in our own favor. Interestingly, a huge majority of kids were actually quite honest about their ability….about 70% for most years. The authors also noted that the younger kids were more likely to be honest than the older kids.

I think this is a really interesting example of how self-reporting biases can play out. It’s easy to think of bias as something that’s big and overwhelming, but studies like this suggest that most bias is small for any given individual. A rounding error here, and accidental report of your grade from last semester….those are tiny for each person but can add up over a group. I suspect if we looked at those older students who reported their grades as inaccurately high, we would discover that they had gotten high grades in previous years. There does seem to be a bias towards reporting your high water mark rather than your current status….kinda like the jock who continues to claim they can run a 5 minute mile long after they cease to be able to do so.

The phenomena is pretty well known, but it’s always interesting to see the hard numbers.

Millenials and Communism

I was perusing Twitter this past weekend when I started to see some concerning headlines float by.

Survey: 1 in 2 millennials would rather live in a socialist or communist country than capitalist one

Millenials think socialism would make a great safe space

Nearly 1 In 5 Millennials Consider Joseph Stalin And Kim Jong Un ‘Heroes’

While I could see a survey of young people turning up with the socialism result, that last headline really concerned me. At first I thought it was just a case of “don’t just read the headline“, but all the articles seemed to confirm the initial statistic. AOL said “a lot of them see Joseph Stalin and Kim Jong Un as “heroes.”” Fox News hit on my discomfort when they said “The report also found that one in five Americans in their 20s consider former Soviet dictator Joseph Stalin a hero, despite his genocide of Ukrainians and Orthodox priests. Over a quarter of millennials polled also thought the same for Vladimir Lenin and Kim Jong Un.”

Seriously?

While I know polls frequently grab headlines by playing on people’s political ignorance, this seemed to go a step beyond that. I had trouble wrapping my head around the idea that anyone in the US could list Stalin, Lenin or Jong-Un as a hero, let alone 20-25%. I had to go see what question prompted such an odd set of results.

The overview of the poll results is here, and sure enough, the question that led to the results is worded a little differently than the article. Here’s the screenshot from the report, blue underlines/boxes are mine:

I think the “hero for their country” part is key. That asks people to assess not just their own feelings, but what they know about the feelings of a whole other country.

Interestingly, I decided to look up Kim Jong-un’s in-country approval rating, and some defectors put it as high as 50%.  According to one poll, 38% of Russians consider Josef Stalin to be the “most outstanding person” in world history. You could certainly debate if those polls had problems in wording, sample or other methodology, but the idea that a 25 year old in the US might see a headline like that and conclude that Russians really did like Stalin doesn’t seem outside the realm of possibility. Indeed, further down the report we find out that only 6% of millenials in the US state that they personally have a favorable view of Stalin. That’s lizard people territory folks.

In this case, it appears the polling company was actually pretty responsible about how they reported things, so it’s disappointing that further reports dropped the “in their country” piece. In my ongoing quest to name different biases and weird ways of skewing data, I’m now wondering what to name this one. What do you call it when someone asks a poll question in a way that encompasses a variety of scenarios, then the later reports shorten the question to make it sound like a different question was answered? I’m gonna work on this.

Daylight Saving (is not the worst of evils)

Well hi there! At this point on Sunday, I’m going to assume you’ve remembered that your clock should have been set back last night. With the advent of cell phones and auto-updates, I suspect the incidence of “showing up to church an hour early because no one remembered daylight saving time” has dropped precipitously since I was a kid.

Growing up, daylight saving time was always the subject of some debate in my house. My dad is a daylight saving time defender, and takes a lot of joy in pointing out to people that no matter how irritated you are by the time change, not changing the time would be even more annoying.

To support his point, I found this site that someone posted on Facebook rather interesting. It’s by a cartographer, and it lets you see the impact of Daylight Saving on the different regions of the country. It also lets you monkey around with different schemes….eliminate daylight saving vs impose it permanently vs keep the status quo…and see what impact they’d have on the sunrise/sunset times. (Note: he created it in 2015, so some numbers may not reflect the 2017 time changes)

My Dad’s point was always that daylight saving blunts the extremes, so I tried out a few different schemes to see how often they made the sunrise very early vs very late. For example, here’s how many days the sun would rise before 5am in different regions if we keep things status quo vs eliminate daylight saving vs always use it:

If you go to the actual website and hover, you can get the exact number of days those colors represent. If we did away with daylight saving, my region of the country would have over 120 days of pre-5am sunrises. I’m an early riser, but that seems a little much even for me.

Here’s how it would effect post-8pm sunsets:

So basically my Dad was right. If you want lots of early sunrises, push to abolish daylight saving. I think most people sort of know that’s what the time change thing is all about, but it is interesting to see exactly how many early sunrises we’re talking about. When you consider that the sky starts to lighten half an hour before sunrise, you realize that getting rid of daylight saving is signing yourself up for a LOT of early morning sunshine.

I think the real PR problem here is that the time changes happen so far away from the extremes that people forget that it’s really designed to help mitigate situations that would occur several months later. I think there’s a new bias name in here somewhere.

The Weight of Evidence

I’ve been thinking a lot about the law and evidence this week, for 3 reasons:

First, this article my lawyer father sent me about the Supreme Court’s aversion to math. It reviews a case about gerrymandering  I’ve mentioned before, and the attempts of statisticians/computer guys to convince the court that their mathematical  models are worth using. While the case hasn’t been decided yet, some researchers were fairly annoyed at how reflexively some of the justices dismissed the models presented, and their invocation of the “gobbledygook” doctrine.

Second was this article I stumbled on that discussed an effort to fact-check supreme court decisions, and found a rather alarming number of them contain factual errors. This one was concerning for two reasons: some of the errors actually appeared to be related to the ultimate decision and some of the errors appear to have come from the Justices doing their own research.

Finally, this article about yet another evidence scandal in my state. Apparently our state lab has been systematically withholding evidence of failed breathalyzer calibrations, calling in to question hundreds of DUI convictions. This is not an aberration…for those of you not from around here, Massachusetts has been on a bad run with our state crime/forensics lab. This is our 3rd major scandal in the past few years, and we now have the dubious distinction of being cited in every report about the problems with forensics.

This got me thinking about a few things:

  1. The line between gobbledygook and “good idea, needs work” is often familiarity. In reading some of the Supreme Courts skepticism of mathematical models and contrasting it with the general acceptance of forensics despite serious concerns, it’s hard not to think that this has something to do with familiarity. Forensics is a science that was quite literally built to support the criminal justice system, whereas computer modeling was built to support….well, all sorts of things. I suspect that’s why one gets more scrutiny than the other.
  2. Mathematical models have to simplify and/or those who build them have prioritize explaining them to people who are not on their side The new wave of mathematical models is intriguing, exciting, and a little bit frightening all at once. Complexity is necessary at times, but ultimately can be used to hide assumptions and get your way. The justices on the Supreme Court know this, and their first suspicion is going to be that all that math is just there to hide something. Anyone hoping to build a model that effects policy should probably keep in mind that for everyone they impress, they will make someone else suspicious. As with any argument, trying it out on someone not inclined to agree with you will teach you a lot about where the holes might be.
  3. Lawyers need to learn more about statistics This one has been the subject of many long talks with my Dad. Unless they were required to take it for their undergrad degree, many lawyers can get through their whole higher ed career without touching a stats class. This seems like a gap to me, especially now that so much of the evidence they’re seeing requires some knowledge of probability and evidence. I’ve mentioned before that doctors struggle with the concept of false positives and false negatives and base rates,  and it seems clear many people in law enforcement do as well.  With all the new types of evidence out there, it seems like this is a gap.
  4. The Supreme Court needs a fact checker Seriously. Are you really telling me there’s not one clerk out there who would be willing to just read through the decisions and find citations for each stat? Or better yet, someone who’d read through each briefing filed with the court and error check them before they got to the Justices? In the case the article cited, the stat in question wasn’t a common controversial one (the % of workplaces that drug tested employees), but the answer provided (88%) apparently had no source at all. I feel like of all groups, the Supreme Court should have figured out how to get this stuff screened out before it biases them.

I am thinking there’s a presentation in here somewhere. If you have any more good articles, send them my way!

It Was a Dark and Stormy Night….

Yes, another short post. There’s a longer one coming Wednesday I promise.

A friend (Ben, of the Pop Science series) put up a challenge on Twitter this week, where he promised that if you replied to his Tweet he would introduce you like you were a character in a novel. I thought you all would appreciate the one he came up with for me;

Now there’s an intro I can get behind. The only thing I’m trying to figure out what genre of book it is. I got kind of a Western vibe, but since I can’t think of a Western plot that involves numbers, I’m thinking space western?  Open to other thoughts on this.

Related: when I’ve had the “who would die first in a horror movie” discussion with friends, it’s pretty much been determined that I’m the pessimist who’s been warning everyone of the danger all along. My death is almost certainly ironic/inevitable. Kind of a cross between a Cassandra and a Harbinger of Impending Doom. Sounds about right.