Bioequivalence and Bioavailability Forum • Inter and Total Variability

Inter and Total Variability [Power / Sample Size]

posted by Ben – 2011-10-06 20:51 (4812 d 22:49 ago) – Posting: # 7438
Views: 12,214

Dear Helmut/all,

I'd like to pick up the topic on how to estimate σ²_inter again.

❝ ❝ And σ²_inter is estimated by (MSE_B - MSE_W)/2 and not MSE_B (in the references you posted these values are plugged in for calculating the corresponding CV, so I guess these values themselves represent direct estimates for the variances).

❝

❝ Right.

When using SAS's PROC MIXED then the variance of the subject effect and the variance of the error term will be printed in the table "Covariance Parameter Estimates". Does SAS internally calculate this estimate by (somehow) using the fact that (MSE_B - MSE_W)/2 ? I found this website which says that SAS calculates (MSE_B - MSE_W)/3. (Example 2; here we have balanced data). I'm confused. Which one is the "correct" estimate? Do I have to multiply the value from SAS by 3 and then divide by 2 to get the "right one"? Does this calculation depend on whether someone uses GLM or MIXED (but the formula (MSE_B - MSE_W)/2 seems to be an general one...)?
Thank you in advance!

Best,
Ben

Complete thread:

Inter and Total Variability Ben 2011-09-02 13:43 [Power / Sample Size]
- Inter and Total Variability Helmut 2011-09-02 14:21
  - Inter and Total Variability Ben 2011-09-03 11:28
    - Inter and Total Variability Ben 2011-09-08 19:22
      - Inter and Total Variability Helmut 2011-09-11 11:55
        
        Inter and Total Variability Ben 2011-09-13 22:03
        
        Inter and Total Variability Helmut 2011-09-14 00:43
        
        Inter and Total Variability Ben 2011-09-18 12:36
        Inter and Total VariabilityBen 2011-10-06 18:51
        
        Inter-subject variance sasophylistic (GLM vs. MIXED) d_labes 2011-10-07 13:33
      - Inter and Total Variability ElMaestro 2011-09-18 14:14
        
        Inter and Total Variability Ben 2011-09-19 19:43