[gambogi]

is there really any reason to expect the students who didn't take free points in exchange for privacy to outperform the observed group?

Sure, the results pertain more to excluding the internet from the classroom, but really that's just splitting hairs imo

[ACow_Adonis]

That could depend on a two part hypothesis that I just came up with off the top of my head:

1) people who are more informed care more about privacy

2) you become more informed by being the type of person who seeks out and successfully obtains information and not being distracted

If 2) and 1) hold, your methodology will be biased to those liable to undertake distracting activities or be distracted. Furthermore, perhaps some would not even partake in the study because it's a distraction relative to why they're in the class in the first place.

Not saying that is demonstrable or true. Don't downvote the hypothetical messenger and all :p

[throwawayjava]

Is there any reason we should be guessing at this when the experimenters could've chosen some other incentive (or none at all)?

And yes, I'd expect weaker students to be the more likely to spend their time / privacy on extra points.