OK, so if take the homosexuality survey as a data point, we can say that selection bias in a survey can increase the reported rate of a behavior by 3 (5% homosexual in normal population, 15% when the survey is about sexual orientation).
If we assume the same increased rate applies in this case, we can divide 5% by three and get 1.666%, still far above the normal 0.36% of the general population.
The ratio could easily be higher than 3:1. The Cognitive Daily survey had a one-question poll right there in the top post on the site’s home page, while this survey required following a link at the bottom of a long post about Asperger’s. That means that this sample was probably more filtered for those who are most motivated and interested in the topic, which will tend to make the sample more biased.
Somewhere around 1% of the people who visited Less Wrong took the poll (82 respondents when there are about 8,000 visitors/day), and it’s not out of the realm of possibility for the response rate among people with Asperger’s to have been 14%, which would be enough to account for the 14:1 ratio between the 5% rate of Asperger’s in the sample and the 0.36% rate in the general population.
It’s hard to estimate the size of a selection effect, especially when the response rate is so low, which makes it hard to undo the bias after the fact to figure out the actual rate. That’s why I’d recommend putting some convention in place for surveys that avoid selection effects as much as possible, if we’re going to try to use surveys to draw conclusions about the LW community.
Also, wanting to take a multiple choice test that outputs a numeric score is going to have a higher correlation with autism/Asperger’s than with homosexuality :)
OK, so if take the homosexuality survey as a data point, we can say that selection bias in a survey can increase the reported rate of a behavior by 3 (5% homosexual in normal population, 15% when the survey is about sexual orientation).
If we assume the same increased rate applies in this case, we can divide 5% by three and get 1.666%, still far above the normal 0.36% of the general population.
The ratio could easily be higher than 3:1. The Cognitive Daily survey had a one-question poll right there in the top post on the site’s home page, while this survey required following a link at the bottom of a long post about Asperger’s. That means that this sample was probably more filtered for those who are most motivated and interested in the topic, which will tend to make the sample more biased.
Somewhere around 1% of the people who visited Less Wrong took the poll (82 respondents when there are about 8,000 visitors/day), and it’s not out of the realm of possibility for the response rate among people with Asperger’s to have been 14%, which would be enough to account for the 14:1 ratio between the 5% rate of Asperger’s in the sample and the 0.36% rate in the general population.
It’s hard to estimate the size of a selection effect, especially when the response rate is so low, which makes it hard to undo the bias after the fact to figure out the actual rate. That’s why I’d recommend putting some convention in place for surveys that avoid selection effects as much as possible, if we’re going to try to use surveys to draw conclusions about the LW community.
Also, wanting to take a multiple choice test that outputs a numeric score is going to have a higher correlation with autism/Asperger’s than with homosexuality :)