I'm a bit perplexed by the developer selection effects.

I get that developers want to use AI. But are they also claiming there's not still a no/low-AI population of developers? Or that their means of selection don't find these developers?

Are they worried that by splitting devs into groups of AI experience they might be measuring some confounder that causes people to choose AI / not AI in their careers?

The study was designed to have devs who are comfortable with AI perform 50% of tasks with AI and 50% without. So the problem is the population of "Developers who use AI regularly but are willing to do tasks without AI" is shrinking.

>> Are they worried that by splitting devs into groups of AI experience they might be measuring some confounder that causes people to choose AI / not AI in their careers?

The developer sample size was small (16 people in the original study) and the task sample size is larger (~250 tasks). I think the worry is variance in developer productivity would totally wash out any signal.

Here is my read:

Developers are refusing to complete the survey or selecting themselves out because they (apparently) don’t want to complete the non-AI task.

The also saw selection effects from a large reduction in the pay for the study (which is an unfortunate confounder here), 150/hr -> 50/hr.

They guess this makes their estimates lower bounds, but the selection effect is complicated (which they acknowledge).

Overall this is a hard problem for them in the current state. It will be challenging to produce convincing year over year analysis under these conditions.