BookmarkSubscribeRSS Feed
nlpurumi
Obsidian | Level 7

Could anyone help me understand following two lines?

 
* random intercept / subject=trial1(subjectid group);   
 
--> Does it mean to report the variance due to a variable "trial"?
--> Is there a possibility that "trial" was treated as "repeated" variable in proc glimmix through this code, because proc glimmix does not have repeated statement?
 
* random _residual_ / group=slc;
--> I think I have a vague sense that residuals are divided by the level of slc through this code, but I am not quite understanding why we divide them. How does it take care of heteroscedasticity problem?
 
Thanks in advance.
2 REPLIES 2
Reeza
Super User

You need to post more code.

What PROC is this part of for starters?

 


@nlpurumi wrote:

Could anyone help me understand following two lines?

 
* random intercept / subject=trial1(subjectid group);   
 
--> Does it mean to report the variance due to a variable "trial"?
--> Is there a possibility that "trial" was treated as "repeated" variable in proc glimmix through this code, because proc glimmix does not have repeated statement?
 
* random _residual_ / group=slc;
--> I think I have a vague sense that residuals are divided by the level of slc through this code, but I am not quite understanding why we divide them. How does it take care of heteroscedasticity problem?
 
Thanks in advance.

 

nlpurumi
Obsidian | Level 7

Because I received a help on this matter through other route, I want to ask a different question.

 

I want to build SAS code to test following equations:

 

Level 1 equation: Yij=β0j+β1j(SLC)+β2j(T)+β3j(SLC*T)+ rij(error)

(i: individual, j: each group)

Level 2 equations:

β0j= γ00+ γ01(G)+u0j

β1j= γ10+ γ11(G)+u1j

β2j= γ20+ γ21(G)+u2j

β3j= γ30+ γ31(G)+u3j

Will this be the good enough codes?

 

proc mixed data=dissertation1 ic;
class group slc subjectid trial1;
model ISI_Avg_sqrt= group|slc /ddfm=kr2 outp=R;
random intercept / subject=subjectid(group);
random slc / subject=subjectid(group);
random intercept / subject=trial1(subjectid group);
repeated /group=trial1;
/*repeated / group=slc;*/
run;

 

Thanks in advance!

sas-innovate-2026-white.png



April 27 – 30 | Gaylord Texan | Grapevine, Texas

Registration is open

Walk in ready to learn. Walk out ready to deliver. This is the data and AI conference you can't afford to miss.
Register now and lock in 2025 pricing—just $495!

Register now

What is ANOVA?

ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.

Find more tutorials on the SAS Users YouTube channel.

Discussion stats
  • 2 replies
  • 1616 views
  • 0 likes
  • 2 in conversation