## total (pooled) variance: examples [Power / Sample Size]

❝ So if we have e.g. 3x6x3 Williams crossover design (with 3 treatments), the number in the denominator depends on the approach we use?

Nevertheless someone else could check it. I read about it many years ago (mentioned here and statistical background somewhere else, I don't remember where). And "a long time ago in a galaxy far, far away" I also recalculated the estimate (obtained from ANOVA - GLM and equation with 3 as denominator) using the mixed model where the inter-subject variability is obtained more directly.

❝ If we use "Two at a Time" approach with incomplete block designs, we are only evaluating 2 treatments and therefore we should use number 2 in the denominator; but if we use "All at Once" approach, we are evaluating all 3 treatments and we have to use number 3 in the denominator?

So: "..., the analysis for each comparison should be conducted excluding the data from the treatments that are not relevant for the comparison in question." (EMA Guideline 1401)

❝ Additional question (just to be sure): we also use number 2 in the denominator (to get inter-subject variance) when we have replicate designs with 2 treatments (regradless of the partial- or full-replicate design)?

### Complete thread:

- Sample size estimation for parallel design Nav Coelho 2007-07-20 16:14 [Power / Sample Size]
- Parallel designs (total variance) Helmut 2007-07-20 16:29
- Parallel designs (total variance) Nav Coelho 2007-07-20 18:38
- CV-intra # 60% CV-inter Helmut 2007-07-22 01:17
- total (pooled) variance: examples Helmut 2007-07-23 17:44
- total (pooled) variance: examples Nav Coelho 2007-07-23 19:58
- total (pooled) variance: examples BEQool 2023-04-18 09:59
- Higher-Order Crossovers Helmut 2023-04-20 10:19
- Higher-Order Crossovers BEQool 2023-04-21 07:53

- total (pooled) variance: examples zizou 2023-04-21 21:23
- total (pooled) variance: examples BEQool 2023-04-22 18:20
- total (pooled) variance: exampleszizou 2023-04-22 21:06
- total (pooled) variance: examples BEQool 2023-04-25 10:57
- total (pooled) variance: examples zizou 2023-04-25 22:43
- total (pooled) variance: examples BEQool 2023-05-04 08:17

- total (pooled) variance: examples zizou 2023-04-25 22:43

- total (pooled) variance: examples BEQool 2023-04-25 10:57

- total (pooled) variance: exampleszizou 2023-04-22 21:06

- total (pooled) variance: examples BEQool 2023-04-22 18:20

- Higher-Order Crossovers Helmut 2023-04-20 10:19

- Parallel designs (total variance) Nav Coelho 2007-07-20 18:38
- Sample size estimation for parallel design Dipesh Jayswal 2007-07-24 08:52

- Parallel designs (total variance) Helmut 2007-07-20 16:29