BookmarkSubscribeRSS Feed
Vivian_pun
Calcite | Level 5

I have a lognormal response variable (depressive score - heavily right skewed), and I run GLIMMIX to assess the assocation between the transformed (DIST=lognormal) score and distance to roadway. I read from a couple previous posts from Mr. Steve Denham that we can get the estimates on the original scale using the forumlas (see image) from the GLIMMIX MODEL statement, DIST options. I have tried it but the back-transformed "original scae" estimates, and the confidence intervals don't make sense to me. If they are back in the original scale, the CI for row 2 that is not statistically signficiant should contain 0, but it is not the case. It looks more like a ratio than mean change. If my math is wrong, please let me know where is the problem. if it is correct, how can I interpret the back-transformed values? I am looking for the interpretation similar to something like "Xx change in the depressive score per 50 meter closer to the main road". 

 

For example, I have the estimate, StdErr, and p-value as the following:

1) -0.0085     0.002541    0.0008

2) -0.00307   0.002115    0.1463

 

The corresponding back-transformed estimate (Ey) variance (VarY), lower and upper CI should be:

1) 0.99154    6.35E-06         0.98661   0.99648

2) 0.99693    4.45E-0.6        0.99280   1.00107

 

Thank you very much. 


Equations.png

sas-innovate-2024.png

Don't miss out on SAS Innovate - Register now for the FREE Livestream!

Can't make it to Vegas? No problem! Watch our general sessions LIVE or on-demand starting April 17th. Hear from SAS execs, best-selling author Adam Grant, Hot Ones host Sean Evans, top tech journalist Kara Swisher, AI expert Cassie Kozyrkov, and the mind-blowing dance crew iLuminate! Plus, get access to over 20 breakout sessions.

 

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
  • 0 replies
  • 1372 views
  • 0 likes
  • 1 in conversation