Data Analysis
Type : CREATION_INTERNE
Data is defined directly in the script (datalines) and concerns death times, censoring, stage, and age at diagnosis.
1 Code Block
DATA STEP Data
Explanation :
Creation of the 'ex1_8b' dataset containing clinical information. Variables are time, censor, stage, age, and year of diagnosis.
Creation of the 'ex1_8b' dataset containing clinical information. Variables are time, censor, stage, age, and year of diagnosis.
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| 1 | DATA ex1_8b; |
| 2 | INPUT time censor stage age_diag yr_diag; |
| 3 | lines; |
| 4 | 0.6 1 1 77 76 |
| 5 | 1.3 1 1 53 71 |
| 6 | 2.4 1 1 45 71 |
| 7 | /* ... données tronquées pour l'affichage ... */ |
| 8 | 4.3 0 4 48 76 |
| 9 | ; |
2 Code Block
DATA STEP Data
Explanation :
Data preparation step: creation of indicator variables (dummy variables) 'stage2', 'stage3', 'stage4' to represent the categorical levels of the 'stage' variable in the regression models.
Data preparation step: creation of indicator variables (dummy variables) 'stage2', 'stage3', 'stage4' to represent the categorical levels of the 'stage' variable in the regression models.
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| 1 | DATA ex1_8b; SET ex1_8b; |
| 2 | title 'Example 1.8, page 9 data -- Death Times of Male Laryngeal Cancer Patients'; |
| 3 | title3 'Proportional Hazards Regression Model -- Local Tests'; |
| 4 | stage2=(stage=2); |
| 5 | stage3=(stage=3); |
| 6 | stage4=(stage=4); |
| 7 | RUN; |
3 Code Block
PROC PRINT
Explanation :
Displays the content of the prepared dataset for verification.
Displays the content of the prepared dataset for verification.
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| 1 | PROC PRINT DATA=ex1_8b; |
| 2 | RUN; |
4 Code Block
PROC PHREG
Explanation :
Cox model including age and stage indicators. TEST statements are used to test the overall effect of stage (no_stage) and perform pairwise comparisons between stages.
Cox model including age and stage indicators. TEST statements are used to test the overall effect of stage (no_stage) and perform pairwise comparisons between stages.
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| 1 | PROC PHREG DATA=ex1_8b; |
| 2 | model time*censor(0) = stage2-stage4 age_diag; |
| 3 | no_stage:test stage2,stage3,stage4; |
| 4 | st2_st3: test stage2=stage3; |
| 5 | st2_st4: test stage2=stage4; |
| 6 | st3_st4: test stage3=stage4; |
| 7 | RUN; |
5 Code Block
PROC PHREG
Explanation :
Second Cox model including only stage indicators (without age), with tests for equality between coefficients of different stages.
Second Cox model including only stage indicators (without age), with tests for equality between coefficients of different stages.
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| 1 | PROC PHREG DATA=ex1_8b; |
| 2 | model time*censor(0) = stage2-stage4; |
| 3 | test stage2=stage3; |
| 4 | test stage3=stage4; |
| 5 | test stage2=stage4; |
| 6 | RUN; |
6 Code Block
PROC LIFETEST
Explanation :
Non-parametric survival analysis (actuarial/Life-Table method, or Kaplan-Meier depending on default options if method=life is not specified; here 'method=life' requests the actuarial method). Produces graphs of the survival function (s) and hazard function (h), stratified by stage.
Non-parametric survival analysis (actuarial/Life-Table method, or Kaplan-Meier depending on default options if method=life is not specified; here 'method=life' requests the actuarial method). Produces graphs of the survival function (s) and hazard function (h), stratified by stage.
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| 1 | PROC LIFETEST DATA=ex1_8b method=life plots=(s,h) graphics; |
| 2 | time time*censor(0); |
| 3 | strata stage; |
| 4 | symbol1 v=none color=red line=1; |
| 5 | symbol2 v=none color=blue line=2; |
| 6 | symbol3 v=none color=green line=3; |
| 7 | RUN; |
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