Later On

A blog written for those whose interests more or less match mine.

Archive for December 26th, 2020

The Dunning-Kruger effect may be an example of the Dunning-Kruger effect

leave a comment »

Being inappropriately confident of a position because of a lack of relevant knowledge — assurance based on ignorance — is often observed, more often in others than in ourselves, but the actual result may in fact be a misinterpretation and misunderstanding of statistics. Jonathan Jarry explains for McGill University’s Office of Science & Society:

Iwant the Dunning-Kruger effect to be real. First described in a seminal 1999 paper by David Dunning and Justin Kruger, this effect has been the darling of journalists who want to explain why dumb people don’t know they’re dumb. There’s even video of a fantastic pastiche of Turandot’s famous aria, Nessun dorma, explaining the Dunning-Kruger effect. “They don’t know,” the opera singer belts out at the climax, “that they don’t know.”

I was planning on writing a very short article about the Dunning-Kruger effect and it felt like shooting fish in a barrel. Here’s the effect, how it was discovered, what it means. End of story.

But as I double-checked the academic literature, doubt started to creep in. While trying to understand the criticism that had been leveled at the original study, I fell down a rabbit hole, spoke to a few statistics-minded people, corresponded with Dr. Dunning himself, and tried to understand if our brain really was biased to overstate our competence in activities at which we suck… or if the celebrated effect was just a mirage brought about by the peculiar way in which we can play with numbers.

Have we been overstating our confidence in the Dunning-Kruger effect?

A misunderstood effect

The most important mistake people make about the Dunning-Kruger effect, according to Dr. Dunning, has to do with who falls victim to it. “The effect is about us, not them,” he wrote to me. “The lesson of the effect was always about how we should be humble and cautious about ourselves.” The Dunning-Kruger effect is not about dumb people. It’s mostly about all of us when it comes to things we are not very competent at.

In a nutshell, the Dunning-Kruger effect was originally defined as a bias in our thinking. If I am terrible at English grammar and am told to answer a quiz testing my knowledge of English grammar, this bias in my thinking would lead me, according to the theory, to believe I would get a higher score than I actually would. And if I excel at English grammar, the effect dictates I would be likely to slightly underestimate how well I would do. I might predict I would get a 70% score while my actual score would be 90%. But if my actual score was 15% (because I’m terrible at grammar), I might think more highly of myself and predict a score of 60%. This discrepancy is the effect, and it is thought to be due to a specific problem with our brain’s ability to assess its skills.

This is what student participants went through for Dunning and Kruger’s research project in the late 1990s. There were assessments of grammar, of humour, and of logical reasoning. Everyone was asked how well they thought they did and everyone was also graded objectively, and the two were compared.

Since then, many studies have been done that have reported this effect in other domains of knowledge. Dr. Dunning tells me he believes the effect “has more to do with being misinformed rather than uninformed.” If I am asked the boiling point of mercury, it is clear my brain does not hold the answer. But if I am asked what is the capital of Scotland, I may think I know enough to say Glasgow, but it turns out it’s Edinburgh. That’s misinformation and it’s pushing down on that confidence button in my brain.

So case closed, right? On the contrary. In 2016 and 2017, two papers were published in a mathematics journal called Numeracy. In them, the authors argued that the Dunning-Kruger effect was a mirage. And I tend to agree.

The effect is in the noise

The two papers, by Dr. Ed Nuhfer and colleagues, argued that the Dunning-Kruger effect could be replicated by using random data. “We all then believed the [1999] paper was valid,” Dr. Nuhfer told me via email. “The reasoning and argument just made so much sense. We never set out to disprove it; we were even fans of that paper.” In Dr. Nuhfer’s own papers, which used both computer-generated data and results from actual people undergoing a science literacy test, his team disproved the claim that most people that are unskilled are unaware of it (“a small number are: we saw about 5-6% that fit that in our data”) and instead showed that both experts and novices underestimate and overestimate their skills with the same frequency. “It’s just that experts do that over a narrower range,” he wrote to me.

Wrapping my brain around all this took weeks. I recruited a husband-and-wife team, Dr. Patrick E. McKnight (from the Department of Psychology at George Mason University, also on the advisory board of Sense About Science and and Dr. Simone C. McKnight (from Global Systems Technologies, Inc.), to help me understand what was going on. Patrick McKnight not only believed in the existence of the Dunning-Kruger effect: he was teaching it to warn his students to be mindful of what they actually knew versus what they thought they knew. But after replicating Dr. Nuhfer’s findings using a different platform (the statistical computing language R instead of Nuhfer’s Microsoft Excel), he became convinced the effect was just an artefact of how the thing that was being measured was indeed measured.

We had long conversations over this as I kept pushing back. As a skeptic, I am easily enticed by stories of the sort “everything you know about this is wrong.” That’s my bias. To overcome it, I kept playing devil’s advocate with the McKnights to make sure we were not forgetting something. Every time I felt my understanding crystallize, doubt would creep in the next day and my discussion with the McKnights would resume.

I finally reached a point where I was fairly certain the Dunning-Kruger effect had not been shown to be a bias in our thinking but was just an artefact. Here then is the simplest explanation I have for why the effect appears to be real.

For an effect of human psychology to be real, it cannot be rigorously replicated using random noise. If the human brain was predisposed to choose heads when a coin is flipped, you could compare this to random predictions (heads or tails) made by a computer and see the bias. A human would call more heads than the computer would because the computer is making random bets whereas the human is biased toward heads. With the Dunning-Kruger effect, this is not the case. Random data actually mimics the effect really well.

The effect as originally described in 1999 makes use of a very peculiar type of graph. “This graph, to my knowledge, is quite unusual for most areas of science,” Patrick McKnight told me. In the original experiment, students took a test and were asked to guess their score. Therefore, each student had two data points: the score they thought they got (self-assessment) and the score they actually got (performance). In order to visualize these results, Dunning and Kruger separated everybody into quartiles:  . . .

Continue reading. There’s much more, and it’s interesting.

Written by LeisureGuy

26 December 2020 at 12:46 pm

Posted in Daily life, Math, Science

Boxing Day Shave: Dead Sea with La Toja Hombre

leave a comment »

RazoRock’s Bruce worked up a very nice lather from The Dead Sea shaving soap because I know that this soap demands that the knot be just barely damp. So I shook the knot well and had no trouble loading it, then after applying the proto-lather to my stubble, I worked in a little more water: lather to perfection.

Yaqi’s DOC is a wonderful razor, easily providing a close shave. A splash of La Toja’s Hombre aftershave, and my skin feels great.

Written by LeisureGuy

26 December 2020 at 11:13 am

Posted in Shaving

<span>%d</span> bloggers like this: