Most of the current studies on therapy dogs for depression has not been done by true experiments either, in that they only suggest correlations but not causation. (topdogtips.com)
Coleman's conclusion was wholly unjustified, because little or none of the EEOS variation in families, schools, peers, or neighborhoods came from true experiments, policy experiments, natural experiments, or any other plausibly exogenous source. (educationnext.org)
This is a true experiment in the sense that we don't know what the outcome will be. (canadianbusiness.com)