Is it correct to calculate the standard deviation error in the cortisol measurement including the first term? In the original paper (CC&Y) it’s not clear how they analyzed the cortisol results: did they averaged the cortisol level at time 1 and the level at time 2? Or did they just averaged the difference of the samples? Because in that second case, you wouldn’t need to account for the variation per person, you just need the average variation (your 2.5) and the inter-assay CV (which you put around 2.8, definitely not something you can left unspecified).
Is it correct to calculate the standard deviation error in the cortisol measurement including the first term? In the original paper (CC&Y) it’s not clear how they analyzed the cortisol results: did they averaged the cortisol level at time 1 and the level at time 2? Or did they just averaged the difference of the samples?
Because in that second case, you wouldn’t need to account for the variation per person, you just need the average variation (your 2.5) and the inter-assay CV (which you put around 2.8, definitely not something you can left unspecified).