> So our farmer should compare a treatment group of turkeys that watches TV with a control group that doesn’t.
For human subjects if you do that you get an "A vs. A+B study" which has a high probability of bias towards intervention B. Just sitting and talking with someone in a white lab coat will improve outcomes over those who do not.
You must compare to some sort of placebo and the closer it is to the intervention you are testing the better. Testing a drug with side effects against an inert placebo can break blinding and show an effect for the drug that isn't there (Type I error.)
This experimental design is very common in the world of So-Called Alternative Medicine (SCAM) e.g. "patients receiving conventional treatment vs. patients receiving conventional treatment plus a chiropractic technique." If you look for this you will find it virtually every time a SCAM practitioner presents an RCT as evidence for its efficacy.
> So our farmer should compare a treatment group of turkeys that watches TV with a control group that doesn’t.
For human subjects if you do that you get an "A vs. A+B study" which has a high probability of bias towards intervention B. Just sitting and talking with someone in a white lab coat will improve outcomes over those who do not.
You must compare to some sort of placebo and the closer it is to the intervention you are testing the better. Testing a drug with side effects against an inert placebo can break blinding and show an effect for the drug that isn't there (Type I error.)
This experimental design is very common in the world of So-Called Alternative Medicine (SCAM) e.g. "patients receiving conventional treatment vs. patients receiving conventional treatment plus a chiropractic technique." If you look for this you will find it virtually every time a SCAM practitioner presents an RCT as evidence for its efficacy.