proc phreg hazard ration levels list for categorical variables and choose reference category

[MFraga]

Hello,

I want to have in the output for a Cox regression (the table with the results for the estimates for maximum likelihood analysis) the list showing the results for each level of the independent variable "independent_v1" or "independent_v2".

My dataset is like this:

data have;

input 

id time1 event1 weight independent_v1 independent_v2;

datalines;

1 0 0 0.8 0 1

1 1 0 0.8 0 1

1 2 0 0.8 0 0

1 3 0 0.8 0 0

1 4 0 0.8 0 1

15 0 0.8 0 1

1 6 0 0.8 0 1

1 7 0 0.8 0 1

1 8 0 0.8 0 2

1 9 0 0.8 0 2

1 10 0 0.8 0 2

1 11 0 0.8 0 2

1 12 0 0.8 0 2

1 13 0 0.8 0 2

2 0 0 1.1 1 0

2 1 1 1.1 1 0

2 2 . 1.1 1 0

3 0 0 1.01 2 1

3 1 0 1.01 2 1

3 2 1 1.01 2 1

3 3 . 1.01 2 1

4 0 1 0.98 2 1

4 1 . 0.98 2 1

4 2 . 0.98 2 1

4 3 . 0.98 2 1

4 4 . 0.98 2 1

5 0 0 1.13 3 0

6 0 0 1.05 3 0

6 1 0 1.05 3 1

6 2 0 1.05 3 1

6 3 0 1.05 3 1

6 4 0 1.05 3 1

6 5 1 1.05 3 1

6 6 . 1.05 3 1

6 7 . 1.05 1 1

6 8 . 1.05 1 1

7 0 0 0.89 0 3

7 1 0 0.89 0 3

7 2 0 0.89 0 3

7 3 0 0.89 0 3

7 4 0 0.89 0 3

7 5 0 0.89 0 3

7 6 0 0.89 0 3

7 7 0 0.89 0 3

7 8 1 0.89 0 1

7 9 . 0.89 0 1

7 10 . 0.89 0 1

8 0 0 1.1 1 0

8 1 0 1.1 1 1

8 2 0 1.1 1 1

8 3 . 1.1 1 2

8 4 . 1.1 1 2

; 

run;

When I code I have the regression results list, but I would like to know how to change the reference category for each independent variable.

My coding:

proc phreg data=have;

class independent_v1 independent_v2;

id id;

model time1*event1(0) = independent_v1 independent_v2;

weight weight;

run;

So SAS automatically chooses to omit one level as the reference category for each independent variable. For example, How I could change that so I choose the reference category 1 for "independent_v1" and 3 for "independent_v2", ?

Thanks for the help!

[ballardw · Accepted solution]

You can add a REF= option to each class variable and specify either the level or Ref=First (for the lowest value)

so

class independent_v1 (ref='category 1') independent_v2 (ref='category 3');

You don't mention which value might be category 1 or 3. the value would the formatted value for the variable concerned and value of interest.

[MFraga]

It works! Thanks!