The method in which the sample is taken from each predefined strata of society is called?
**Core Concept:** Sampling is a method used in research to collect a representative sample of individuals or items from a larger population to study or make inferences about the population as a whole. In stratified sampling, the population is divided into subgroups or strata based on certain criteria, and samples are drawn from each stratum to ensure proportional representation.
**Why the Correct Answer is Right:** Stratified sampling (C) is a type of sampling technique where the population is divided into subgroups (strata) based on specific characteristics or criteria. This method ensures that each stratum gets a proportional representation in the sample, reflecting the distribution of the population's characteristics.
**Why Each Wrong Option is Incorrect:**
A. Simple random sampling (D) does not consider the subgroups and randomly selects samples from the entire population, which may lead to an unrepresentative sample and biased results.
B. Systematic sampling (A) involves selecting individuals at fixed intervals, which may result in uneven representation of subgroups and affect the accuracy of the study's conclusions.
E. Cluster sampling (B) involves selecting clusters of individuals or units (e.g., households or schools) and then randomly selecting individuals or units from each cluster. This method does not involve dividing the population into strata but rather focuses on selecting clusters.
**Why Each Wrong Option is Incorrect:**
E. Quota sampling (D) involves determining the number of individuals to be selected from each stratum based on predetermined quotas, ensuring proportional representation but lacks randomness and may lead to selection bias.
**Clinical Pearl:** A well-designed stratified sampling method helps maintain the representativeness of the sample and reduces bias, enabling more accurate conclusions about the population based on the study's findings.