Patients Are Being Studied for Their Satisfaction Within a Physician

Multiple Choice

Patients are being studied for their satisfaction within a physician practice. The strata divide these patients into groupings by the variables of age, sex, insurance type, and physician. The strata are then used for a random selection of patients to assure an even selection for the variables in question. Which type of sampling is this an example of?

A) Cluster samples
B) Simple random samples
C) Systemic random samples
D) Stratified random samples