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uzma03505621
Obsidian | Level 7

I am using Proc transreg to identify which link function will be appropriate for my dependent variable in the GLM model. I used the code as follows:

 

proc transreg data=finalfile;
model boxcox(cost/lambda=-1 to 2 by .5)=identity(&variablelist);
run;

 

 

I get an error
ERROR: 24 invalid values were encountered while attempting to transform variable cost. Is it because my dependent variable has 24 observations with zero costs.

How can I resolve this issue

 

As I changed the code by adding parameter=1

It works giving me the following output and that lamba=0 is selected


The TRANSREG Procedure
TRANSREG Univariate Algorithm Iteration History for BoxCox(cost)
Iteration
Number
Average
Change
Maximum
Change
R-Square Criterion
Change
Note
1 0.00000 0.00000 0.15025   Converged



Algorithm converged.

 

 

 

Please assist me with right method. Thank you

2 REPLIES 2
jiltao
SAS Super FREQ

Your Lambda list includes 0, which is the log transformation. Log of 0 is undefined, and that is why you received that error message.

You might want to exclude these observations, at least for lambda=0.

WarrenKuhfeld
Rhodochrosite | Level 12

https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_transreg_details02.htm

 

As you figured out, you can specify PARAMETER= to add a value to each datum to avoid log 0 and other invalid operations. There are many other ways to get nonlinear transformations in TRANSREG and other procedures.

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