[everythingswan]

This is more of an exploration than an explanation but it seems like you're pointing to the threshold of success in a series of experiments.

As deyan mentioned in physics or chemistry, we get a high level of certainty after isolating all the variables. When it doesn't go according to plan, it's a known or unknown variable to blame.

It seems to me that behavioral psychology is still in its infancy in terms of identifying those variables and/or the threshold of Truth is much lower than sciences like chemistry.

Lots of patterns exist that have lower thresholds. Sports analogies are fairly illustrative. Hitters in baseball are considered great if they succeed 3 times out of 10. Then again, they run 500+ experiments a year (for hopefully many years) to determine their average...

I agree with your conclusion that experiments needed to be repeated more over time. I simply wonder what type of success threshold we will look at as the Truth in time.