The scientific consensus on marijuana is still up in the air, but it seems to be falling in favor of marijuana with each passing day. In order to provide a survey of the various research that’s been done on the topic, we put together a list of 30 studies about pot use from the past few years.

These studies found both positive and negative outcomes associated with cannabis but show just how the recent scientific findings have started to track with popular opinion — in that more research is finding positive outcomes with marijuana use while the populous is leaning toward legalization just about everywhere.

The most important thing to remember when reading this list is that a large percentage of studies about marijuana are based on correlation — observed conditions in subjects who use or have used marijuana — which makes their validity hard to determine. In fact, the great majority of correlation studies are never proven to be correct. That is, the factors surrounding the condition either include something else that caused the condition or cannot be conclusively reduced to a single cause.

Causation studies on the other hand are much more reliable, because through study design marijuana or other drug can be shown to directly cause an effect. However, these studies are much harder to come by mostly because marijuana is an illegal substance and funding for studies requires the use of cannabis grown for and controlled by the feds, so increases in the number of research projects is muted.