I'm not aware of those studies related to the Ioannides paper, but the story on replication in psychology and specifically social psychology is not at all prett

I'm not aware of those studies related to the Ioannides paper, but the story on replication in psychology and specifically social psychology is not at all pretty. My sense is that there are research domains that are functional, but others (social, clinical psychology) which are not at all. Given the level of motivated cognition and sloppy thinking evident in decades of psychiatric and other research into cannabis use, I wouldn't be at all surprised to find low standards in studies of this type. I'm not saying that's the case, but it's certainly my prior when reading any dietary studies, or studies of "bad effect x" of recreational drugs. In general, when publishing any study like this the research should be contextualised properly. For example, it would make sense to state the effect size in relation to the risk of drinking 10% more than the recommended units of alcohol, or smoking 20 cigarettes per day.