Stat Computing > SAS > Textbook Examples > Applied Survival Analysis, Second Edition

SAS Textbook Examples
Applied Survival Analysis by Hosmer, Lemeshow and May
Chapter 9: Other Models and Topics

The psoriasis data set is used in this chapter. We present table 9.2 below. The rest of the chapter has been skipped for now. We will complete it as time permits.

Table 9.2, page 293

* AG model;
proc sort data = psrecur;
  by id;
run;
data psrecur1;
  set psrecur;
  by id;
  time0 = lag(time2);
  if first.id then time0 = 0;
run;
ods select ParameterEstimates;
proc phreg data = psrecur1 covs(aggregate);
  model (time0 time2)*status(0) = tape light yrspsor;
  id id;
run;

The PHREG Procedure

                   Analysis of Maximum Likelihood Estimates

               Parameter    Standard  StdErr                            Hazard
Variable  DF    Estimate       Error   Ratio  Chi-Square  Pr > ChiSq     Ratio

TAPE       1     0.39008     0.12445   0.577      9.8243      0.0017     1.477
LIGHT      1     0.40134     0.12118   0.571     10.9691      0.0009     1.494
YRSPSOR    1     0.00899     0.00558   0.482      2.5972      0.1071     1.009

* PWP-CP model;
data psrecur2;
  set psrecur;
  retain enum ;
  by id;
  time0 = lag(time2);
  if first.id then do;
   time0 = 0;
   enum = 1;
  end;
  else enum = enum + 1;
run;
ods select ParameterEstimates;
proc phreg data = psrecur2 covs(aggregate);
  model (time0 time2)*status(0) = tape light yrspsor;
  strata enum;
  id id;
run;

The PHREG Procedure

                   Analysis of Maximum Likelihood Estimates

               Parameter    Standard  StdErr                            Hazard
Variable  DF    Estimate       Error   Ratio  Chi-Square  Pr > ChiSq     Ratio

TAPE       1     0.83831     0.24985   1.012     11.2574      0.0008     2.312
LIGHT      1     1.11766     0.26807   0.992     17.3833      <.0001     3.058
YRSPSOR    1     0.02102     0.01366   1.044      2.3700      0.1237     1.021

* PWP-GT model;
data psrecur3;
  set psrecur;
  retain enum;
  by id;
  zero_time = 0;
  lagtime = lag(time2);
  if first.id then do;
    time_diff= time2;
	enum = 1;
  end;
  else do;
    enum = enum + 1;
    time_diff = time2 - lagtime;
   end;
run;
ods select ParameterEstimates;
proc phreg data = psrecur3 covs(aggregate);
  model (zero_time time_diff)*status(0) = tape light yrspsor;
  strata enum;
  id id;
run;

The PHREG Procedure

                   Analysis of Maximum Likelihood Estimates

               Parameter    Standard  StdErr                            Hazard
Variable  DF    Estimate       Error   Ratio  Chi-Square  Pr > ChiSq     Ratio

TAPE       1     0.61630     0.24510   1.055      6.3226      0.0119     1.852
LIGHT      1     0.81123     0.22350   0.964     13.1741      0.0003     2.251
YRSPSOR    1     0.01583     0.01234   0.974      1.6454      0.1996     1.016

*WLW;
data psrecur4;
   set psrecur2;
   retain new_enum;
   by id;
   if first.id then new_enum = 1;
   else new_enum = new_enum + 1;
   if last.id then do;
      output;
      if enum < 4 then do i = 1 to 4-enum;
      new_enum= new_enum + 1;
	  output;
	  end;
   end;
   if ~last.id then output;
   drop enum;
run;
ods select ParameterEstimates;
proc phreg data = psrecur4 covs(aggregate);
  model time2*status(0) = tape light yrspsor;
  strata new_enum;
run;

The PHREG Procedure

                   Analysis of Maximum Likelihood Estimates

               Parameter    Standard  StdErr                            Hazard
Variable  DF    Estimate       Error   Ratio  Chi-Square  Pr > ChiSq     Ratio

TAPE       1     1.02995     0.22369   0.920     21.2008      <.0001     2.801
LIGHT      1     1.54021     0.20916   0.825     54.2267      <.0001     4.666
YRSPSOR    1     0.02778     0.01267   0.940      4.8074      0.0283     1.028

*TT-R;
ods select ParameterEstimates;
proc phreg data = psrecur3 covs(aggregate);
  model time2*status(0) = tape light yrspsor;
  strata enum;
run;

The PHREG Procedure

                   Analysis of Maximum Likelihood Estimates

                 Parameter     Standard   StdErr                               Hazard
Variable   DF     Estimate        Error    Ratio   Chi-Square   Pr > ChiSq      Ratio

TAPE        1      0.95533      0.22480    0.920      18.0593       <.0001      2.600
LIGHT       1      1.44791      0.20670    0.808      49.0689       <.0001      4.254
YRSPSOR     1      0.02581      0.01231    0.925       4.3962       0.0360      1.026

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