Originally Posted by mgcsinc

This is demonstrably false.

Demonstration:

You said that no one except people who are flying on Y/B/M's are getting upgrade rates in the 80-90% range.

There are people on DidItClear who have. (I think; I haven't actually checked, because I'm lazy.)

EDIT to add a less snarky response: I've dealt with the misimpression that self-selection kills the cat before, again in the context of brain imaging, psychology, etc. studies. Doing statistics was my job.

There is a group of people that insist that those studies can never have any validity because many of them require the subjects to affirmatively seek them out. The fact is that there is a space between that and Fox News. I think DidItClear is in that space.

When you do a statistical test, you calculate a p value that is supposed to represent the likelihood of the outcome you observed occurring in the presence of the null hypothesis. There's always some possibility that random chance produced the effect -- you're just looking to make sure that that possibility is very small. DidItClear can absolutely be used to make such assessments.

Here's an example of how that would work, taken to the extreme. Let's say that I have a hypothesis that at least 10% of 1K's are obtaining CPU's on at least 80% of their flights. Let's also say that I know that there are 1,000 1K's out there. Let's say I pull up DidItClear and it shows that 50 1K's have reported their stats, and they all have CPU rates of at least 80%. That effect could come from one of three places: (1) facts about the entire population, (2) self-selection bias, or (3) random chance. There is sufficient information in this example for a statistical model to assign the likely amounts at which each of those factors contribute to the effect.