But, as you are aware, criticism of early parapsychology experiments by outsiders led to improvements in experimental design, and yet results continued to be statistically significant. So, what you appear to be left with is that most parapsychology experiments have not used control groups, which I'm not sure explains the results.
Yeah, reducing the effects of a few of the biases removed 'the effect' which had been presumed to represent psi. So we are left with a residual 'effect' in the presence of additional biases. You can see why anyone who wants to cling to that residual 'effect' would avoid using experimental designs which could eliminate what is left.
Linda