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You can use the recode statement with all procedures in SUDAAN (except proc records). This statement is especially useful when you need to create a categorical variable from a continuous variable. The original continuous variable is recoded "on the fly", and the recoded variable is not added to your data set; rather, it exists only for the duration of the procedure. In the first example below, a 0/1 variable is created from the continuous variable ab23. A cut-off value of 50 is given, so in the recoded variable, values less than 50 will be coded 0 and values equal to and greater than 50 will be coded 1. Please see page 164 of the SUDAAN manual for more information regarding the recode statement. On the var statement, you need to specify the variable one time for each level of that variable that appears on the catlevel statement. On the catlevel statement, you need to specify the value of each level of the variable that you want displayed in the output.
proc descript data=temp1 filetype=sas design = jackknife; weight rakedw0; jackwgts rakedw1--rakedw80 / adjjack=1; recode ab23 = (50); var ab23 ab23; catlevel 0 1; run;
S U D A A N
Software for the Statistical Analysis of Correlated Data
Copyright Research Triangle Institute January 2003
Release 8.0.2
Number of observations read : 55428 Weighted count : 23847415
Denominator degrees of freedom : 80
Variance Estimation Method: Replicate Weight Jackknife
by: Variable, One.
-----------------------------------------------------
| | |
| Variable | | One
| | | 1 |
-----------------------------------------------------
| | | |
| Age first told | Sample Size | 3709 |
| by doctor that | Weighted Size | 1380250.55 |
| have diabetes | Total | 709750.87 |
| or sugar | Percent | 51.42 |
| diabetes: 0 - | SE Percent | 1.03 |
| HIGH | | |
-----------------------------------------------------
| | | |
| Age first told | Sample Size | 3709 |
| by doctor that | Weighted Size | 1380250.55 |
| have diabetes | Total | 670499.68 |
| or sugar | Percent | 48.58 |
| diabetes: 0 - | SE Percent | 1.03 |
| HIGH | | |
-----------------------------------------------------
In the example below, the recode statement is used to create a three-level variable from the continuous variable ab23. In the recoded variable, values less than 20 will be coded as 0, values less than or equal to 30 will be coded as 1, and values less than 70 will be coded as 2.
proc descript data=temp1 filetype=sas design = jackknife; weight rakedw0; jackwgts rakedw1--rakedw80 / adjjack=1; recode ab23 = (20 30 70); var ab23 ab23 ab23; catlevel 0 1 2; run;
----------------------------------------------------- | | | | Variable | | One | | | 1 | ----------------------------------------------------- | | | | | Age first told | Sample Size | 3709 | | by doctor that | Weighted Size | 1380250.55 | | have diabetes | Total | 76494.78 | | or sugar | Percent | 5.54 | | diabetes: 0 - | SE Percent | 0.52 | | HIGH | | | ----------------------------------------------------- | | | | | Age first told | Sample Size | 3709 | | by doctor that | Weighted Size | 1380250.55 | | have diabetes | Total | 113516.38 | | or sugar | Percent | 8.22 | | diabetes: 0 - | SE Percent | 0.58 | | HIGH | | | ----------------------------------------------------- | | | | | Age first told | Sample Size | 3709 | | by doctor that | Weighted Size | 1380250.55 | | have diabetes | Total | 1055360.64 | | or sugar | Percent | 76.46 | | diabetes: 0 - | SE Percent | 0.88 | | HIGH | | | -----------------------------------------------------
The example below shows how you can use the recode statement to recode a 0/1 variable into a 1/2 variable. Although this is not needed for proc descript, this is used because the recoding is so clearly shown in the output.
data temp01; set temp1; newvar1 = 0; if _n_ ge 4050 then newvar1 = 1; run; proc descript data=temp01 filetype=sas design = jackknife; weight rakedw0; jackwgts rakedw1--rakedw80 / adjjack=1; recode newvar1 = (0 1); var newvar1 newvar1; catlevel 1 2; run;
S U D A A N
Software for the Statistical Analysis of Correlated Data
Copyright Research Triangle Institute January 2003
Release 8.0.2
Number of observations read : 11000 Weighted count : 4801259
Denominator degrees of freedom : 80
Variance Estimation Method: Replicate Weight Jackknife
by: Variable, One.
-----------------------------------------------------
| | |
| Variable | | One
| | | 1 |
-----------------------------------------------------
| | | |
| NEWVAR1: 1 | Sample Size | 11000 |
| | Weighted Size | 4801258.85 |
| | Total | 1763363.22 |
| | Percent | 36.73 |
| | SE Percent | 0.58 |
-----------------------------------------------------
| | | |
| NEWVAR1: 2 | Sample Size | 11000 |
| | Weighted Size | 4801258.85 |
| | Total | 3037895.63 |
| | Percent | 63.27 |
| | SE Percent | 0.58 |
-----------------------------------------------------
The example below shows how you can use the recode statement to recode a 1/2 variable into a 0/1 variable. According to the SUDAAN website, you cannot use the recode statement to recode a value of 2 to 0 (2 = 0).
data temp01a; set temp01; if newvar1 = 0 then newvar2 = 1; if newvar1 = 1 then newvar2 = 2; run; proc descript data=temp01a filetype=sas design = jackknife; weight rakedw0; jackwgts rakedw1--rakedw80 / adjjack=1; recode newvar2 = (2 3); var newvar2 newvar2; catlevel 0 1; run;
----------------------------------------------------- | | | | Variable | | One | | | 1 | ----------------------------------------------------- | | | | | NEWVAR2: 0 | Sample Size | 55428 | | | Weighted Size | 23847415.32 | | | Total | 1763363.22 | | | Percent | 7.39 | | | SE Percent | 0.15 | ----------------------------------------------------- | | | | | NEWVAR2: 1 | Sample Size | 55428 | | | Weighted Size | 23847415.32 | | | Total | 22084052.10 | | | Percent | 92.61 | | | SE Percent | 0.15 | -----------------------------------------------------
The values on the recode statement temporarily recode newvar2 to be a 0/1 variable for use as a dependent variable in a logistic regression.
proc rlogist data=temp01a filetype=sas design = jackknife; weight rakedw0; jackwgts rakedw1--rakedw80 / adjjack=1; recode newvar2 = (2 3); model newvar2 = racehpra ae21a ab23; subgroup racehpra; levels 4; run;
S U D A A N
Software for the Statistical Analysis of Correlated Data
Copyright Research Triangle Institute January 2003
Release 8.0.2
Number of zero responses : 37
Number of non-zero responses : 404
Independence parameters have converged in 8 iterations
Number of observations read : 55428 Weighted count: 23847415
Observations used in the analysis : 441 Weighted count: 221626
Denominator degrees of freedom : 80
Maximum number of estimable parameters for the model is 6
Sample and Population Counts for Response Variable NEWVAR2
0: Sample Count 37 Population Count 27513
1: Sample Count 404 Population Count 194113
R-Square for dependent variable NEWVAR2 (Cox & Snell, 1989): 0.022326
-2 * Normalized Log-Likelihood with Intercepts Only : 330.83
-2 * Normalized Log-Likelihood Full Model : 320.87
Approximate Chi-Square (-2 * Log-L Ratio) : 9.96
Degrees of Freedom : 4
Note: The approximate Chi-Square is not adjusted for clustering.
Refer to hypothesis test table for adjusted test.
Variance Estimation Method: Replicate Weight Jackknife
Working Correlations: Independent
Link Function: Logit
Response variable NEWVAR2: NEWVAR2
----------------------------------------------------------------------
Independent P-value
Variables and Beta T-Test
Effects Coeff. SE Beta T-Test B=0 B=0
----------------------------------------------------------------------
Intercept 0.45 0.96 0.47 0.6399
Race - UCLA CHPR
Definition
LATINO 0.50 0.44 1.12 0.2642
PACIFIC ISLANDER inf . . .
AIAN 2.54 0.81 3.13 0.0024
ASIAN 0.00 0.00 . .
Minutes doing
walking or
bicycling 0.01 0.01 1.52 0.1329
Age first told by
doctor that have
diabetes or sugar
diabetes 0.02 0.02 0.94 0.3491
----------------------------------------------------------------------
-------------------------------------------------------
Contrast Degrees
of P-value
Freedom Wald F Wald F
-------------------------------------------------------
OVERALL MODEL 5 33.64 0.0000
MODEL MINUS
INTERCEPT 4 3.16 0.0182
INTERCEPT . . .
RACEHPRA 2 4.91 0.0097
AE21A 1 2.30 0.1329
AB23 1 0.89 0.3491
-------------------------------------------------------
-----------------------------------------------------------
Independent
Variables and Lower 95% Upper 95%
Effects Odds Ratio Limit OR Limit OR
-----------------------------------------------------------
Intercept 1.57 0.23 10.63
Race - UCLA CHPR
Definition
LATINO 1.64 0.68 3.94
PACIFIC ISLANDER . . .
AIAN 12.64 2.52 63.27
ASIAN 1.00 1.00 1.00
Minutes doing
walking or
bicycling 1.01 1.00 1.03
Age first told by
doctor that have
diabetes or sugar
diabetes 1.02 0.98 1.05
-----------------------------------------------------------
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