If you knew the regression to the mean time, on average, for each condition tested, yes (null is true vs false). However, to quantify the absolute effects, you need a no placebo arm.
If you knew the regression to the mean time, on average, for each condition tested, yes (null is true vs false). However, to quantify the absolute effects, you need a no placebo arm.
Hmm, that's a good point, though I'm not sure you have to have regression to the mean time... As long as I have multiple data points pretreatment (so that I can establish a reliable baseline), don't I only need to show that on average, patients were stable before intervention-->improved on intervention-->regressed post? Also, if this is the case, why can't I look at average score pre-intervention vs avg during placebo treatment and quantify effect that way?
A study long ago by C Edward Davis et al showed that if a patient passes a triple screen (3 successive clinic visits) for LDL cholesterol > 190 there is still regression to the mean with a surprising proportion of patients having LDL < 190 immediately before randomization to a cholesterol lowering drug.
If you knew the regression to the mean time, on average, for each condition tested, yes (null is true vs false). However, to quantify the absolute effects, you need a no placebo arm.
Hmm, that's a good point, though I'm not sure you have to have regression to the mean time... As long as I have multiple data points pretreatment (so that I can establish a reliable baseline), don't I only need to show that on average, patients were stable before intervention-->improved on intervention-->regressed post? Also, if this is the case, why can't I look at average score pre-intervention vs avg during placebo treatment and quantify effect that way?
A study long ago by C Edward Davis et al showed that if a patient passes a triple screen (3 successive clinic visits) for LDL cholesterol > 190 there is still regression to the mean with a surprising proportion of patients having LDL < 190 immediately before randomization to a cholesterol lowering drug.