Biostats grad student here. "But the probability of this study having failed to control for some other variable is higher than..." It was a randomized block e

Biostats grad student here. "But the probability of this study having failed to control for some other variable is higher than..." It was a randomized block experiment. You don't need to assume that there were no unmeasured confounders in order to make causal inferences. That assumption is only needed in cross-sectional and cohort studies.