Natural Recovery Time - PROC LIFEREG Example

This script illustrates the use of the LIFEREG procedure to analyze survival data with arbitrary (interval) censoring. It models the relationship between recovery time, age, and sex, including an interaction. Two analyses are performed to generate probability plots (probplots) based on specific reference data (xrow1 and xrow2).

Data Analysis

Type : CREATION_INTERNE

All data (tables 'mice', 'xrow1', 'xrow2') are defined directly in the script via DATALINES blocks.

1 Code Block

DATA STEP Data

Explanation :
Creation of the main 'mice' dataset containing the explanatory variables (sex, age) and the time interval bounds (time1, time2).

Copied!

1	title 'Natural Recovery Time';
2	DATA mice;
3	INPUT sex age time1 time2;
4	DATALINES;
5	1 57 631 631
6	1 45 . 170
7	1 54 227 227
8	1 43 143 143
9	1 64 916 .
10	1 67 691 705
11	1 44 100 100
12	1 59 730 .
13	1 47 365 365
14	1 74 1916 1916
15	2 79 1326 .
16	2 75 837 837
17	2 84 1200 1235
18	2 54 . 365
19	2 74 1255 1255
20	2 71 1823 .
21	2 65 537 637
22	2 33 583 683
23	2 77 955 .
24	2 46 577 577
25	;

2 Code Block

DATA STEP Data

Explanation :
Creation of a reference dataset 'xrow1' for prediction or plotting (Sex 1, Age 50).

Copied!

1	DATA xrow1;
2	INPUT sex age time1 time2;
3	DATALINES;
4	1 50 . .
5	;

3 Code Block

DATA STEP Data

Explanation :
Creation of a second reference dataset 'xrow2' (Sex 2, Age 60.6).

Copied!

1	DATA xrow2;
2	INPUT sex age time1 time2;
3	DATALINES;
4	2 60.6 . .
5	;

4 Code Block

PROC LIFEREG

Explanation :
Execution of the Weibull survival model with 'mice' data. The 'xdata=xrow1' option is used to customize the probability plot. The 'model' statement defines the censoring bounds (time1, time2) and the covariates.

Copied!

1	ods graphics on;
2	PROC LIFEREG DATA=mice xdata=xrow1;
3	class sex;
4	model (time1, time2) = age sex age*sex / dist=Weibull;
5
6	probplot / nodata
7	plower=.5
8	vref(intersect) = 75
9	vreflab = '75 Percent';
10	inset;
11	RUN;

5 Code Block

PROC LIFEREG

Explanation :
Second execution of the model, identical to the first, but using 'xrow2' as reference data for the plot.

Copied!

1	PROC LIFEREG DATA=mice xdata=xrow2;
2	class sex;
3	model (time1, time2) = age sex age*sex / dist=Weibull;
4
5	probplot / nodata
6	plower=.5
7	vref(intersect) = 75
8	vreflab = '75 Percent';
9	inset;
10	RUN;
11	title;

This material is provided "as is" by We Are Cas. There are no warranties, expressed or implied, as to merchantability or fitness for a particular purpose regarding the materials or code contained herein. We Are Cas is not responsible for errors in this material as it now exists or will exist, nor does We Are Cas provide technical support for it.

Retour à la liste