Question

in stratified sampling, how are strata defined?
a. by selecting every nth member to form a stratum
b. by characteristics shared within each group
c. by randomly dividing the population
d. by the geographical location of members

Explanation:

Stratified sampling divides the population into subgroups (strata). These strata are defined by shared characteristics within each group. Option a is systematic sampling. Option c is simple random sampling. Option d is too narrow as strata can be defined by various characteristics (not just geography).

Answer:

B. By characteristics shared within each group