Starter Example 1 for PROC LIFEREG

The script begins by creating a dataset named 'Headache' directly within the script using the `datalines` statement. This dataset contains variables for duration in minutes, treatment group, and a censoring indicator. After data creation, the script displays the first five observations of the 'Headache' dataset using PROC PRINT for a quick check. The main procedure is PROC LIFEREG, which is used to model survival data. It specifies 'Minutes' as the survival time variable, 'Censor' as the censoring status variable (where 1 indicates a censored event), and 'Group' as the explanatory classification variable. This procedure generates a new dataset 'New' which includes the cumulative distribution function (CDF) under the variable 'Prob'. Finally, PROC SGPLOT is employed to visualize the analysis results by generating a scatter plot. This plot represents 'Minutes' on the X-axis and 'Prob' (CDF) on the Y-axis, with data points grouped and colored according to the 'Group' variable, and a discrete legend is added for easier interpretation.

Data Analysis

Type : INTERNAL_CREATION

The 'Headache' dataset is created directly within the script using the `datalines` statement, providing data for survival analysis. The 'New' dataset is an intermediate result from PROC LIFEREG.

1 Code Block

DATA STEP Data

Explanation :
This DATA STEP block creates a SAS dataset named 'Headache'. The variables 'Minutes', 'Group', and 'Censor' are defined. Data is read in-line via the `datalines` statement, simulating results from a clinical trial or study with observation times and censoring indicators.

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1	DATA Headache;
2	INPUT Minutes Group Censor;
3	DATALINES;
4	11 1 0 12 1 0 19 1 0 19 1 0
5	19 1 0 19 1 0 21 1 0 20 1 0
6	21 1 0 21 1 0 20 1 0 21 1 0
7	20 1 0 21 1 0 25 1 0 27 1 0
8	30 1 0 21 1 1 24 1 1 14 2 0
9	16 2 0 16 2 0 21 2 0 21 2 0
10	23 2 0 23 2 0 23 2 0 23 2 0
11	25 2 1 23 2 0 24 2 0 24 2 0
12	26 2 1 32 2 1 30 2 1 30 2 0
13	32 2 1 20 2 1
14	;

2 Code Block

PROC PRINT

Explanation :
This block uses PROC PRINT to display the first five observations (rows) of the 'Headache' dataset. This is a common step to quickly verify the structure and content of the data after its creation or modification.

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1	PROC PRINT DATA=headache (obs=5);
2	RUN;

3 Code Block

PROC LIFEREG Data

Explanation :
This block executes PROC LIFEREG to perform an accelerated survival regression analysis on the 'Headache' dataset. The 'Group' variable is specified as a classification variable. The `model` statement defines the regression model, where 'Minutes' is the survival time variable, 'Censor' is the censoring status variable (with 1 indicating censoring, i.e., an unobserved event), and 'Group' is the explanatory variable. The `output` statement creates a new dataset 'New' that contains the original observations along with a new variable 'Prob' representing the estimated cumulative distribution function (CDF).

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1	PROC LIFEREG DATA=Headache;
2	class Group;
3	model Minutes*Censor(1)=Group;
4	OUTPUT out=New cdf=Prob;
5	RUN;

4 Code Block

PROC SGPLOT

Explanation :
This block uses PROC SGPLOT to generate a graphical visualization. It creates a scatter plot from the 'New' dataset created by PROC LIFEREG. 'Minutes' are represented on the X-axis and 'Prob' (CDF) values on the Y-axis. The `/ group=Group` option colors the data points according to the categories of the 'Group' variable, and `discretelegend` adds a discrete legend to identify these groups.

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1	PROC SGPLOT DATA=New;
2	scatter x=Minutes y=Prob / group=Group;
3	discretelegend;
4	RUN;

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