Test for partial correlation between pairs of variables in the x
and y
input matrices, while controlling for the effects of a third set of variables.
Load the sample data. Convert the genders in hospital.Sex
to numeric group identifiers.
Create three matrices containing the sample data.
partialcorr
can test for partial correlation between the pairs of variables in x
(the systolic and diastolic blood pressure measurements) and y
(weight and age), while controlling for the variables in z
(gender and smoking status). The measurements for BloodPressure
are contained in two columns: The first column contains the upper (systolic) number, and the second column contains the lower (diastolic) number. partialcorr
treats each column as a separate variable.
Test for partial correlation between pairs of variables in x
and y
, while controlling for the effects of the variables in z
. Compute the correlation coefficients.
rho = 2×2
-0.0257 0.1289
0.0292 0.0472
pval = 2×2
0.8018 0.2058
0.7756 0.6442
The results in pval
indicate that, after controlling for gender and smoking status, there is no significant correlation between either of a patient’s blood pressure measurements and that patient’s weight or age.
For a clearer display, create tables with appropriate variable and row labels.
Partial Correlation Coefficients
Weight Age
________ ________
BPTop -0.02568 0.12893
BPBottom 0.029168 0.047226
Weight Age
_______ _______
BPTop 0.80182 0.2058
BPBottom 0.77556 0.64424