It seems quite likely to me that all the results on creatine and cognition are bogus, maybe I’d bet at 4:1 against there being a real effect >0.05 SD.
Unless I’m misunderstanding, does this mean you’d bet that the effects are even smaller than what this study found on its preregistered tasks? If so, do you mind sharing why?
Yes, I’d bet the effects are even smaller than what this study found. This study gives a small amount of evidence of an effect > 0.05 SD. But without a clear mechanism I think an effect of < 0.05 SD is significantly more likely. One of the main reasons we were expecting an effect here was a prior literature that is now looking pretty bad.
That said, this was definitely some evidence for a positive effect, and the prior literature is still some evidence for a positive effect even if it’s not looking good. And the upside is pretty large here since creatine supplementation is cheap. So I think this is good enough grounds for me to be willing to fund a larger study.
Unless I’m misunderstanding, does this mean you’d bet that the effects are even smaller than what this study found on its preregistered tasks? If so, do you mind sharing why?
Yes, I’d bet the effects are even smaller than what this study found. This study gives a small amount of evidence of an effect > 0.05 SD. But without a clear mechanism I think an effect of < 0.05 SD is significantly more likely. One of the main reasons we were expecting an effect here was a prior literature that is now looking pretty bad.
That said, this was definitely some evidence for a positive effect, and the prior literature is still some evidence for a positive effect even if it’s not looking good. And the upside is pretty large here since creatine supplementation is cheap. So I think this is good enough grounds for me to be willing to fund a larger study.