Bioequivalence and Bioavailability Forum

Group effect: the endless river [General Statistics]

posted by PharmCat – Russia, 2019-12-22 23:52 (1758 d 13:13 ago) – Posting: # 21019
Views: 8,158
(edited on 2019-12-23 17:04)

Hi!

❝ Is it right that we can simply neglect the structure of this term as we can do in standard models with Subject instead of Subject(Sequence)?

Edited.

You can use just "Subject" in random statement in SAS. I think if you try to do this, you should get the same results. Of course, if your subject numbers not repeated.

Data:

DATA data;

infile datalines dlm=" " truncover;

input subject $ house $ room $ var;

datalines;

1 1 1 4

1 1 1 6

2 1 1 6

2 1 1 10

3 1 2 2 

3 1 2 4

4 1 2 2

4 1 2 3

5 2 3 8

5 2 3 10

6 2 3 6

6 2 3 10

7 2 4 4

7 2 4 6

;

RUN;

Code 1

PROC MIXED data=data; 

CLASSES subject house room;

MODEL  var = house room/ DDFM=SATTERTH solution;

RANDOM subject/V G;

ESTIMATE 'house' house -1 1/e;

RUN;

Fixed effect without denoted nested factors: problem with results, but coefficient calculated correctly.

Code 2


PROC MIXED data=data; 

CLASSES subject house room;

MODEL  var = house room(house)/ DDFM=SATTERTH solution;

RANDOM subject/V G;

ESTIMATE 'house' house -1 1/e;

RUN;

Fixed effect with nested factor: no problems, but Subjects in Dimensions = 1. Look at horrible V matrix. In this case it does not matter, but it not corresponds with reality.

Code 3

PROC MIXED data=data; 

CLASSES subject house room;

MODEL  var = house room(house)/ DDFM=SATTERTH solution;

RANDOM intercept/SUBJECT=subject V G;

ESTIMATE 'house' house -1 1/e;

RUN;

Good fit. Subjects in Dimensions = 8. We have individual V matrices and ready for structuring.

Code 4


PROC MIXED data=data; 

CLASSES subject house room;

MODEL  var = house room(house)/ DDFM=SATTERTH solution;

RANDOM intercept/SUBJECT=subject(room) V G;

ESTIMATE 'house' house -1 1/e;

RUN;

Nested random part - no effect.

I can't find any difference between subject and subject(room). As I understand nested factors affect on fixed part. I don't know how nested statment can affect on random part, but I think - in this case there is no effect.

Complete thread:

Group by sequence interaction Mutasim 2019-08-07 13:16 [General Statistics]
- Group by sequence interaction, an urban myth? Helmut 2019-08-07 14:35
  - pristine, genuine, holy, magnificent, inexplicable beautiful variation ElMaestro 2019-08-08 10:06
    - I love your subject line! Helmut 2019-08-08 10:31
      - Group effect, did you miss it? Astea 2019-12-21 14:12
        
        Group effect, did you miss it? PharmCat 2019-12-22 01:37
        Group effect: the endless story Helmut 2019-12-22 10:30
        
        Group effect: the endless river Astea 2019-12-22 21:23
        
        Group effect: the endless riverPharmCat 2019-12-22 22:52
        replicateBE solution with interactions mittyri 2019-12-23 14:30
        
        replicateBE solution with interactions Astea 2019-12-23 17:26
        
        datasets issues mittyri 2019-12-24 10:53
        datasets Helmut 2019-12-24 11:03
        
        datasets Astea 2019-12-24 19:18
        
        lmer / lme Helmut 2019-12-25 19:12
        
        What do you mean exactly? Beholder 2019-12-27 13:44
        
        What do you mean exactly? Astea 2019-12-29 21:59
        
        ANOVA acc. to GL Helmut 2019-12-30 12:32

Group effect: the endless river [General Sta­tis­tics]

Complete thread:

Group effect: the endless river [General Statistics]