Hello,
I would appreciate if someone could provide me with a better approach to solve the problem.
My main aims are
a. count the number of cases(ca case) and controls (pop cont) not exposed to any of the the 4 agents (a1, a2,a3 and a4 ) from the dataset agents_expt (Table 1) below. Exposed is 1 and unexposed is zero (0).
Results: 3 ca cases and 7 pop cont obtained(Table 2). -Step 1 of SAS code
b.Create/name the results obtained in Table 2(ie. subjects unexposed to any of the agents as a reference group(refgroup) for the purpose of comparison.-Step 2 of SAS code
c. Find the estimates (odds ratio) for the refgroup and other variables including income.-step 3 of SAS code.
Looks like my SAS code are too long to achieve the above aims.
I would appreciate if someone could provide me with a better approach to solve the problem.
*Pls note: For the purpose of this test approach, let us ignore the warning:quasi-separation of points(as there are inadequate data) . If the code works for this test data, I am sure it will work for the original dataset too.
My dataset, code and log are found below; results are attached.
Thanks in advance for your expertise.
ak.
/* Logistic test ref group test*/
data agents_expt;
input id$ a1 a2 a3 a4 lung$ 14-21 income 23-29;
datalines;
os1 1 0 0 1 ca case 45424
os2 1 1 0 0 ca case 52877
os3 0 0 0 0 pop cont 25600
os4 1 0 0 1 pop cont 14888
os5 0 0 0 0 ca case 41036
os6 0 0 0 0 ca case 20365
os7 1 0 1 1 pop cont 16988
os8 0 0 0 0 ca case 100962
os9 1 0 1 0 pop cont 11230
os10 0 0 1 0 ca case 35850
os11 0 1 0 0 pop cont 28700
os12 0 0 0 0 pop cont 46320
os13 1 1 1 1 pop cont 24897
os14 0 0 0 0 pop cont 18966
os15 1 0 0 1 ca case 20540
os16 0 0 1 0 pop cont 150600
os17 1 1 1 1 pop cont 24897
os18 0 0 0 0 pop cont 17999
os19 0 0 0 0 pop cont 22540
os20 0 0 0 0 pop cont 158600
os21 0 0 0 0 pop cont 187365
os22 1 0 1 0 ca case 30580
;
run;
proc print data=agents_expt;
Title 'Table 1: Exposure of ids to 4 agents';
/*Step 1: Finding number of cases and controls unexposed to agents(a1,a2,a3 and a4)*/
proc freq data=agents_expt(where=(sum(a1,a2,a3,a4)=0));
tables lung;
title 'Table 2:Subjects unexposed to any of the 4 agents';
run;
/*Step 2:Using subjects unexposed to any of agents as a ref. group*/
proc sql;
create table t as
select
id, a1, a2, a3,a4,lung, income,
sum(a1,a2,a3,a4)=0 as refgroup
from agents_expt
;
quit;
proc print data=t;
title 'Table 3: original variables and ref group';
run;
proc freq data=t;
tables lung* refgroup;
title 'Table 4: freq of ca case and pop cont for ref group';
run;
/*Step 3: Finding odds ratio estimates for variables including ref.group*/
/* LOGISTIC REG. TEST*/
data logtest; set t;/*P stands for Pooled*/
if lung in ('ca case','pop cont');
run;
proc logistic data=logtest;
/*class cla_scat (param=ref ref ='0');*/
/*model lung(event='Ca case') = cla_expf age cigcsi;*/
model lung(event='ca case') =a1 a2 a3 a4 refgroup income;
Title 'Table 5: Estimates for variables including ref. group';
run;
OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
72
73
74 /* Logistic test ref group test*/
75 data agents_expt;
76 input id$ a1 a2 a3 a4 lung$ 14-21 income 23-29;
77 datalines;
NOTE: The data set WORK.AGENTS_EXPT has 22 observations and 7 variables.
NOTE: DATA statement used (Total process time):
real time 0.01 seconds
cpu time 0.01 seconds
100 ;
101 run;
102 proc print data=agents_expt;
103 Title 'Table 1: Exposure of ids to 4 agents';
104
105 /*Step 1: Finding number of cases and controls unexposed to agents(a1,a2,a3 and a4)*/
NOTE: There were 22 observations read from the data set WORK.AGENTS_EXPT.
NOTE: PROCEDURE PRINT used (Total process time):
real time 0.27 seconds
cpu time 0.27 seconds
106 proc freq data=agents_expt(where=(sum(a1,a2,a3,a4)=0));
107 tables lung;
108 title 'Table 2:Subjects unexposed to any of the 4 agents';
109 run;
NOTE: There were 10 observations read from the data set WORK.AGENTS_EXPT.
WHERE SUM(a1, a2, a3, a4)=0;
NOTE: PROCEDURE FREQ used (Total process time):
real time 0.13 seconds
cpu time 0.11 seconds
110
111 /*Step 2:Using subjects unexposed to any of agents as a ref. group*/
112
113 proc sql;
114 create table t as
115 select
116 id, a1, a2, a3,a4,lung, income,
117 sum(a1,a2,a3,a4)=0 as refgroup
118 from agents_expt
119 ;
NOTE: Table WORK.T created, with 22 rows and 8 columns.
120 quit;
NOTE: PROCEDURE SQL used (Total process time):
real time 0.01 seconds
cpu time 0.02 seconds
121
122 proc print data=t;
123 title 'Table 3: original variables and ref group';
124 run;
NOTE: There were 22 observations read from the data set WORK.T.
NOTE: PROCEDURE PRINT used (Total process time):
real time 0.22 seconds
cpu time 0.23 seconds
125
126 proc freq data=t;
127 tables lung* refgroup;
128 title 'Table 4: freq of ca case and pop cont for ref group';
129 run;
NOTE: There were 22 observations read from the data set WORK.T.
NOTE: PROCEDURE FREQ used (Total process time):
real time 0.15 seconds
cpu time 0.14 seconds
130
131 /*Step 3: Finding odds ratio estimates for variables including ref.group*/
132
133 /* LOGISTIC REG. TEST*/
134 data logtest; set t;/*P stands for Pooled*/
135 if lung in ('ca case','pop cont');
136 run;
NOTE: There were 22 observations read from the data set WORK.T.
NOTE: The data set WORK.LOGTEST has 22 observations and 8 variables.
NOTE: DATA statement used (Total process time):
real time 0.01 seconds
cpu time 0.01 seconds
137
138 proc logistic data=logtest;
139 /*class cla_scat (param=ref ref ='0');*/
140 /*model lung(event='Ca case') = cla_expf age cigcsi;*/
141 model lung(event='ca case') =a1 a2 a3 a4 refgroup income;
142 Title 'Table 5: Estimates for variables including ref. group';
143 run;
NOTE: PROC LOGISTIC is modeling the probability that lung='ca case'.
WARNING: There is possibly a quasi-complete separation of data points. The maximum likelihood estimate may not exist.
WARNING: The LOGISTIC procedure continues in spite of the above warning. Results shown are based on the last maximum likelihood
iteration. Validity of the model fit is questionable.
NOTE: There were 22 observations read from the data set WORK.LOGTEST.
NOTE: PROCEDURE LOGISTIC used (Total process time):
real time 0.44 seconds
cpu time 0.41 seconds
144
145
146 OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
158
