Chp. 7 Verms - Sampling: Estimating the Frequency of Behaviors and Beliefs

population

(also population of interest) a larger group from which a sample is drawn; the group to which a study’s conclusions are intended to be applied

sample

the group of people, animals, or cases used in a study; a subset of the population of interest

census

a set of observations that contains all members of the population of interest

biased sample

(also unrepresentative sample) a sample in which some members of the population of interest are systematically left out and, therefore, the results cannot generalize to the population of interest

unbiased sample

(representative sample) a sample in which all members of the population of interest are equally likely to be included (usually through some random method), and therefore the results can generalize to the population of interest

convenience sampling

choosing a sample based on those who are easiest to access and readily available; a biased sampling technique

self-selection

a form of sampling bias that occurs when a sample contains only people who volunteer to participate

probability sampling

(also random sampling) a category name for random sampling techniques, such as simple random sampling, stratified random sampling, and cluster sampling, in which a sample is drawn from a population if interest so each member has an equal and known chance of being included in the same

non probability sampling

a category name for nonrandom sampling techniques, such as convenience, purposive, and quota sampling, that result in a biased sample

simple random sampling

the most basic form of probability sampling, in which the sample is chosen completely at random from the population of interest (e.g., drawing names out of a hat)

systematic sampling

a probability sampling techniques in which the researcher uses a randomly chosen number N, and counts off every Nth member of a population to achieve a sample

cluster sampling

a probability sampling technique in which clusters of participants within the population of interest are selected at random, followed by data collection from all individuals in each cluster

multistage sampling

a probability sampling technique involving at least two stages: a random sample of cluster followed by a random sample of people within the selected clusters

stratified random sampling

a form of probability sampling; a random sampling technique in which the researcher identifies particular demographic categories, or strata, and then randomly selects individuals within each category

oversampling

a form of probability sampling, a variation of stratified random sampling in which the researcher intentionally overrepresents one or more groups

purposive sampling

a biased sampling technique in which only certain kinds of people are included in a sample

snowball sampling

a variation on purposive sampling, a biased sampling technique in which participants are asked to recommend acquaintances for the study

quota sampling

a biased sampling technique in which a researcher identifies subsets of the population of interest, sets a target number for each category in the sample, and nonrandomly selects individuals within each category until the quotas are filled