PROC TRANSREG AND ANOVA

[#1]

What would be the procedure equivalent to proc transreg for ANOVAS (categorical IV's)? We are looking to use boxcox transformations on a continuous DV. 

[#2]

Hello @ANKH1,

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[#3]

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@ANKH1 wrote:

What would be the procedure equivalent to proc transreg for ANOVAS (categorical IV's)? We are looking to use boxcox transformations on a continuous DV. 

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You would want to use the CLASS transformation of the MODEL statement.

[#4]

Hi,
I tried the following:
74 proc transreg data = sample1;
75 model boxcox(DV)=class(CAT);
76 run;

ERROR: 11 invalid values were encountered while attempting to transform variable DV.

The 11 invalid values are from values=0. Moreover, when I write

proc transreg data = sample1;
model boxcox(DV/lambda=1)=class(IV);
run;

It shows exactly the same error.

[#5]

Are you sure that the error is not because you have negative values of DV?

Please show us a portion of your data set SAMPLE1, following these instructions: https://communities.sas.com/t5/SAS-Communities-Library/How-to-create-a-data-step-version-of-your-dat...

[#6]

Hi, 

Thank you for your answer.

We don't have negative values in that DV. I tried following the code you provided to show our data but I guess I couldn't figured out how since our data set is an imported excel file with approx 19900 rows and 80 columns. 

I tried the code with another DV to see if it could be another reason, but again it showed an error for one value. I checked for that DV and that one value seems to be again coming from only one value = 0. 

[#7]

As an experiment, run the PROC TRANSREG on a data set which doesn't have 0 values for Y using

model boxcox(DV/lambda=1)=class(IV);

and see if the error goes away.

[#8]

It did run! 

[#9]

Okay, but I can't explain why 0 is considered an invalid value for Y in the Box-Cox transformation with λ=1. Maybe @PGStats or @ballardw has some insight here. Or you could always talk to SAS tech support.

[#10]

Thank you!

[#11]

---

@ANKH1 wrote:

Hi, 

Thank you for your answer.

We don't have negative values in that DV. I tried following the code you provided to show our data but I guess I couldn't figured out how since our data set is an imported excel file with approx 19900 rows and 80 columns. 

I tried the code with another DV to see if it could be another reason, but again it showed an error for one value. I checked for that DV and that one value seems to be again coming from only one value = 0. 

---

How exactly did you check for negative values? Since you say that you "imported" and Excel file there are times when, depending on the display settings in Excel  very small magnitude negative value, such as -0.000001, could appear as 0.00 with the default 2 decimals in Excel and Proc Import might honor that setting or just not show if the value has a BEST format associated.

Consider:

data example;
   x= -0.00001;
   format x best4.;
   put x= ;
run;

The log will show x=0. As would a table view or proc print.

This may be a long shot but "mystery" behaviors sometimes require examining the less common issues.

[#12]

That's an interesting thought.

This implies that @ANKH1 ought to do something like

proc print data=sample1(where=(dv<0));

[#13]

Or use PROC MEANS to examine the minimum:

proc means data=sample1 fw=18 macdec=16;
   var dv;
run;

[#14]

Hi, 

I ran the code and didn't get any negative values. 

[#15]

So, that's not it, but I don't really have any other suggestions about what might be causing this. I would still contact SAS Tech support to see if they have an explanation.