My god, I just found a reason for sociologists to study intro economics.
Next Big What - people don't exercise more even if you pay them to go to the gym. But the study has a big problem:
690 people who joined a private gym in an unidentified Midwestern city from September 2015 to April 2016 were divided into four groups. A control group received a $30 gift card after six weeks regardless of attendance.
The others received gift cards of either $30 or $60, or a gift worth about $30, only if they went to the gym at least nine days in their first six weeks of membership.
The study noted new gym members were “extremely overoptimistic about how often they will visit the gym, and there is a fast decline in their visit frequency over the first few months of membership.” On average, they said they’d go about three times a week, but started off going twice a week and after a couple of months were exercising just once a week.
Differences between people who were and weren’t paid to work out were “quite modest,” the researchers wrote.
The paid participants went, on average, 0.14 more times per week than the control group. That difference largely disappeared after the six-week program ended.
The problem is, your study only found that their reservation price for going to the gym is higher than $30/9 or $60/9.
If you'd paid them $50 per gym visit you'd have found more people going.
This is such a simple error, from the standpoint of bloody first-year bullshit economics, that I wonder why every single sociological/psychological study has been structured to give out such a shitty low reward.