"To point out the absurdity of this study using only 31 users with varying degrees of other types of drug use, as well as measuring some highly subjective metric, "
That is the reason they gave publicly, not the reason they don't like the study.
The study used participants without a history of other drug use.
And having the effect appear with only 31 randomly sampled users means the effect is easy to detect. This is a normal number of participants for this sort of study.
You see this sort of motivated reaction to a study every time there is one that triggers a population.
" You see this sort of motivated reaction to a study every time there is one that triggers a population. "
This is true, but in both directions.
Because unlike you said, they actually only tested 31 cannabis users against a controll group of 40. And found that maybe subtle differences exist.
"Speech samples were collected from a carefully described cohort of 31 adults with a history of cannabis use (but not use of illicit stimulant drugs) and 40 non-drug-using controls."
"Subtle differences in speech timing, vocal effort, and voice quality may exist between cannabis and control groups, however data remain equivocal"
> they actually only tested 31 cannabis users against a controll group of 40
This is exactly like I said. In fact nothing you say contradicts anything I've said, so I'm not sure what point you're trying to make.
Adding more participants would measure the same subtle difference with increasing precision, but it's unclear what the point of that would be.*
The next logical step is to look further into voice effects, since the voice effect (along with the similar motor effects) are just easily measurable proxies for other changes going on in the brain.
Generally, if one's criticism of a study uses only concepts you learn about in the first day of intro to statistics (e.g. "correlation does not imply causation" or "there are only N participants"), then chances are pretty low that one has discovered a serious flaw that was missed by the authors and reviewers.
*We can get into a wider discussion about power here, but that tends to be pretty subtle and nothing at all about the power of the study merits it being called absurd.
"nothing at all about the power of the study merits it being called absurd. "
Well, I have not read the paper in detail, because I do not want to buy it. So I would not claim it to be absurd in its whole.
But what I can read is that the title of it makes a factual statement, while in the text you find the word "maybe". So "absurd" might be fitting for that.
And 31 is a really, really low number, for the goal:
"The aim of this study was to investigate speech in individuals with a history of recreational cannabis use compared to non-drug-using healthy controls. "
Like others have said, there is a strong influence of subculture speech patterns.
Have 10 rastafarie influenced people in the group and sure you will notice difference in the speech pattern. And difference does not necessarily mean "worse". I would have to read the paper to judge what they exactly meassured. And of course, how much the "recreational use" of the person involved was. Because intuitivly: sure, a person smoking 10+ joints a day speaks different, if at all, compared to the normal person.
I think it's fair to criticize a study if you think the headline (or the popular writeup) oversells it. However, my reading here is that the abstract basically says
"It's possible that W, X, Y, and Z are different in our populations. However we can't conclude that because after doing the appropriate controls, we only find that Y and Z differ."
The existence of Y and Z differences is itself sufficient to justify the language in the headline. What the authors are pointing out is that there are some obvious other variables to check, and they checked them, but their measurements weren't precise enough to detect differences in all of them.
> Have 10 rastafarie influenced people in the group and sure you will notice difference in the speech pattern.
But obviously this is not what they did. Again, this fails the basic sniff test of whether your criticism uses concepts more difficult than day 1 of statistics 101.
Yes it is possible that the cannabis sample is biased in some way. But the point is it's not biased in any obvious way. The same is true of any scientific study. All of Newtonian physics was biased against objects moving near light speed. That doesn't make it absurd or bad, it just means you had to keep measuring things until you found out what the bias was.
> And difference does not necessarily mean "worse".
Sure, but in this case it does. Intensity was decreased and the speech was more effortful.
> And of course, how much the "recreational use" of the person involved was.
This is the reason he does not like the study.