Bioequivalence and Bioavailability Forum • Least Square Means (LSM) for unequal sequence

Least Square Means (LSM) for unequal sequence [Regulatives / Guidelines]

posted by ElMaestro – Denmark, 2011-10-03 16:51 (5012 d 05:58 ago) – Posting: # 7410
Views: 15,723

Dear yicaoting,

❝ 1. How to calculate LSM and SE for each Treatment? I want to manually calculate it, can anyone give me some exact equation?

❝ I have read WNL's user guide, it didn't tell me the exact equation. Only reads "(computed by LinMix)," on page 332 of WNL 5.1's User Guide

❝ 2. Why SE of the two treatments are identical?

1. You take the Mean of T in Seq TR and the mean of T in Seq RT. You add them and divide by two. Do the same for R.

2. The crucial variability for a 2,2,2-BE design from which the 90% CI is derived is the residual sigma (which is your [pseudo-]within variability). Since there is no true replication of neither T nor R you cannot derive a within-subject variability separately for T or R. Think of it in matrix terms: Your error matrix is just a bunch of zeros and with the common sigma on the diagonal.

—
Pass or fail!
ElMaestro

Complete thread:

Least Square Means (LSM) for unequal sequence yicaoting 2011-10-03 14:37 [Regulatives / Guidelines]
- Least Square Means (LSM) for unequal sequenceElMaestro 2011-10-03 14:51
  - Least Square Means (LSM) for unequal sequence yicaoting 2011-10-03 15:28
    - Least Square Means (LSM) for unequal sequence ElMaestro 2011-10-03 15:36
    - Least Square Means (LSM) for unequal sequence Helmut 2011-10-03 16:14
      - Least Square Means (LSM) for unequal sequence ElMaestro 2011-10-03 20:10
  - Least Square Means (LSM) for unequal sequence Pankaj Bhangale 2011-10-04 14:52
    - Weighted Means? Helmut 2011-10-05 01:53
- LSM for unbalanced sequences -SAS- d_labes 2011-10-04 09:39
  - LSM for unbalanced sequences -SAS- yicaoting 2011-10-04 19:37
    - SE for unbalanced sequences SAS vs. WinNonlin Helmut 2011-10-05 01:01
    - LS Means mean? d_labes 2011-10-05 12:45
      - LS Means mean? ElMaestro 2011-10-05 13:23
      - PHX/WNL vs. SAS Helmut 2011-10-08 02:21
        
        PHX/WNL vs. SAS Proc Mixed d_labes 2011-10-10 15:46
        
        PHX/WNL vs. SAS Proc Mixed Helmut 2011-10-10 16:30
        
        PHX/WNL vs. SAS Proc Mixed ElMaestro 2011-10-10 19:53
        
        Real mixed effects in WNL, SAS, GLM or Mixed (1) yicaoting 2011-10-13 18:39
        Real mixed effects in WNL, SAS, GLM or Mixed (2) yicaoting 2011-10-13 18:52
        Real mixed effects in WNL, SAS, GLM or Mixed (3) yicaoting 2011-10-13 19:05
        
        Must admit I am lost ElMaestro 2011-10-14 00:02
        
        Must admit I am lost yicaoting 2011-10-14 06:30
        
        Must admit I am lost - edited ElMaestro 2011-10-14 13:23