People, no offense to those who might be reading, are conceited nitwits who think they're far better at things than they actually are. But it also turns out there are certain situations in which they are convinced they're way worse than they actually are. Here's how low self-esteem strikes a blow against accuracy.
In general, we think we're pretty great at everything. Ninety-three percent of drivers consider themselves above average, most employees think they are above the average level of their division, and about a third of workers think they're in the top 5% of their group. There's just something in us that makes us feel like we're doing pretty good compared to nearly everyone else. It's gained the nickname "The Lake Wobegon effect" because of the novel Lake Wobegon Days, by Garrison Keillor, about the little town of Lake Wobegon, Minnesota, where "all the children are above average." Knowing little-to-nothing about the subject doesn't ameliorate the effect. The now-infamous Dunning-Kruger effect shows that people who lack basic knowledge about a subject lack the experience to understand how little they know, and vastly overestimate their comprehension of the subject.