Picking a specific definition of a word, expounding its consequences, and then referring to the colloquial usage of the word as a “myth” is just word-play as I said.
Many do think of confounders in an experimental context as just those effects which correlate with both outcome and treatment. The non-sequitur — barring a specific definition — is concluding that since nothing can correlate with random allocation, confounders are impossible by construction.
Why impossible? Because we are talking about the probability of allocation, not the actual allocation, and confounding does not refer to the result. We’d instead say there are imbalanced covariates, but that’s ok because randomisation converts “imbalance into error”. Yet, the covariates may be unknown, and without taking measurements prior to the treatment, how are we supposed to know whether the treatment itself or just membership of the treatment group explains the group differences?
Had we not tested the samples prior to treatment, the result would be what many would call “confounded” by the differences in the samples prior to treatment.
The best available defense against the possibility of spurious results due to confounding is often to dispense with efforts at stratification and instead conduct a randomized study of a sufficiently large sample taken as a whole, such that all potential confounding variables (known and unknown) will be distributed by chance across all study groups and hence will be uncorrelated with the binary variable for inclusion/exclusion in any group.
Many do think of confounders in an experimental context as just those effects which correlate with both outcome and treatment. The non-sequitur — barring a specific definition — is concluding that since nothing can correlate with random allocation, confounders are impossible by construction.
Why impossible? Because we are talking about the probability of allocation, not the actual allocation, and confounding does not refer to the result. We’d instead say there are imbalanced covariates, but that’s ok because randomisation converts “imbalance into error”. Yet, the covariates may be unknown, and without taking measurements prior to the treatment, how are we supposed to know whether the treatment itself or just membership of the treatment group explains the group differences?
Had we not tested the samples prior to treatment, the result would be what many would call “confounded” by the differences in the samples prior to treatment.
From https://en.wikipedia.org/wiki/Confounding#Decreasing_the_pot..., please note the use of the word:
The best available defense against the possibility of spurious results due to confounding is often to dispense with efforts at stratification and instead conduct a randomized study of a sufficiently large sample taken as a whole, such that all potential confounding variables (known and unknown) will be distributed by chance across all study groups and hence will be uncorrelated with the binary variable for inclusion/exclusion in any group.