Results: InferenceForTheDifferenceOfTwoProportions.sas

leading question regarding gun permits example (success = favor permit)

The FREQ Procedure

The Freq Procedure

Table group * response

Cross-Tabular Freq Table

Frequency
Row Pct
Table of group by response
group response(favor permit)
favor not Total
leadingQ
403
68.89
182
31.11
585
 
neutralQ
463
75.28
152
24.72
615
 
Total
866
334
1200

Column 1 Risk Estimates

Column 1 Risk Estimates
  Risk ASE 95%
Confidence Limits		 Exact 95%
Confidence Limits
Difference is (Row 1 - Row 2)
Row 1 0.6889 0.0191 0.6514 0.7264 0.6496 0.7262
Row 2 0.7528 0.0174 0.7188 0.7869 0.7168 0.7865
Total 0.7217 0.0129 0.6963 0.7470 0.6954 0.7469
Difference -0.0640 0.0259 -0.1146 -0.0133    

Risk Difference Test

Risk Difference Test
H0: P1 - P2 = 0    Wald Method
Column 1 (response = favor)
Risk Difference -0.0640
ASE (Sample) 0.0259
Z -2.4729
One-sided Pr < Z 0.0067
Two-sided Pr > |Z| 0.0134

HIV vaccine trial (success = positive)

The FREQ Procedure

The Freq Procedure

Table group * response

Cross-Tabular Freq Table

Frequency
Row Pct
Table of group by response
group response(HIV status)
positive negative Total
vaccine
241
6.70
3357
93.30
3598
 
control
126
6.98
1679
93.02
1805
 
Total
367
5036
5403

Column 1 Risk Estimates

Column 1 Risk Estimates
  Risk ASE 95%
Confidence Limits		 Exact 95%
Confidence Limits
Difference is (Row 1 - Row 2)
Row 1 0.0670 0.0042 0.0588 0.0752 0.0590 0.0756
Row 2 0.0698 0.0060 0.0581 0.0816 0.0585 0.0826
Total 0.0679 0.0034 0.0612 0.0746 0.0614 0.0750
Difference -0.0028 0.0073 -0.0171 0.0115    

Risk Difference Test

Risk Difference Test
H0: P1 - P2 = 0    Wald Method
Column 1 (response = positive)
Risk Difference -0.0028
ASE (Sample) 0.0073
Z -0.3867
One-sided Pr < Z 0.3495
Two-sided Pr > |Z| 0.6990

West of Scotland coronary prevention study: 5 years (success=yes)

The FREQ Procedure

The Freq Procedure

Table drug * response

Cross-Tabular Freq Table

Frequency
Row Pct
Table of drug by response
drug response(has a coronary event)
yes no Total
pravastatin
174
5.27
3128
94.73
3302
 
placebo
248
7.53
3045
92.47
3293
 
Total
422
6173
6595

Column 1 Risk Estimates

Column 1 Risk Estimates
  Risk ASE 95%
Confidence Limits		 Exact 95%
Confidence Limits
Difference is (Row 1 - Row 2)
Row 1 0.0527 0.0039 0.0451 0.0603 0.0453 0.0609
Row 2 0.0753 0.0046 0.0663 0.0843 0.0665 0.0849
Total 0.0640 0.0030 0.0581 0.0699 0.0582 0.0702
Difference -0.0226 0.0060 -0.0344 -0.0108    

Risk Difference Test

Risk Difference Test
H0: P1 - P2 = 0    Wald Method
Column 1 (response = yes)
Risk Difference -0.0226
ASE (Sample) 0.0060
Z -3.7555
One-sided Pr < Z <.0001
Two-sided Pr > |Z| 0.0002

West of Scotland coronary prevention study: 15 years (success=yes)

The FREQ Procedure

The Freq Procedure

Table drug * response

Cross-Tabular Freq Table

Frequency
Row Pct
Table of drug by response
drug response(has a coronary event)
yes no Total
pravastatin
390
11.81
2912
88.19
3302
 
placebo
509
15.46
2784
84.54
3293
 
Total
899
5696
6595

Column 1 Risk Estimates

Column 1 Risk Estimates
  Risk ASE 95%
Confidence Limits		 Exact 95%
Confidence Limits
Difference is (Row 1 - Row 2)
Row 1 0.1181 0.0056 0.1071 0.1291 0.1073 0.1296
Row 2 0.1546 0.0063 0.1422 0.1669 0.1424 0.1674
Total 0.1363 0.0042 0.1280 0.1446 0.1281 0.1448
Difference -0.0365 0.0084 -0.0530 -0.0199    

Risk Difference Test

Risk Difference Test
H0: P1 - P2 = 0    Wald Method
Column 1 (response = yes)
Risk Difference -0.0365
ASE (Sample) 0.0084
Z -4.3201
One-sided Pr < Z <.0001
Two-sided Pr > |Z| <.0001