PSCY 217 Chapter 4

Population

a set of people of interest to the researcher

Sample

subset or small portion of the population, data is used to try and understand something about the larger population from which the sample was drawn

External validity

findings based on a sample can be generalized to an entire population of interest - sample needs to be representative of the population from which it is drawn, need responses from every person in the selected sample

Sampling frame

the actual population of people from which a random, sample will be drawn, which is often a subset of the population of interest, it will rarely perfectly coincide with the entire population of interest, some biases will be introduced

Response rate

the percentage of people in the sample who actually complete the survey

Probability sampling

each member of the population has a known and specific probability of being chosen, allows for representative samples, allowing the results from samples to be generalized to the population from which they were drawn

Non-probability sampling

we don’t know the probability of any particular member of the population being chosen, this has implications for the generalizability of any results based on the sample, difficulties with probability sampling means non-probability sampling is quite common and can be necessary in certain circumstances

Simple random sampling

every member of the population has an equal probability of being selected for the sample

Random sample

whenever people are randomly selected from a specific population to participate in a study

Stratified random sampling

the population is divided into subgroups (or strata) an then simple random sampling is used to select sample members from each group

Cluster sampling

the researcher identifies “clusters“ of people and then samples from these clusters, after the clusters are chosen, all people in each cluster are included in the sample

Convenience sampling

non probability sampling, participants are recruited wherever you can find them

Purposive sampling

non-probability sampling for a specific purpose to obtain a sample of people who meet some predetermined criterion

Quota sampling

non-probability sampling, researcher chooses a sample that reflects the numerical composition of various subgroups in the population. thus quota sampling is similar to the stratified sampling procedure without randomness

Sampling error

the error in our estimate of the value that exists in the population, because it is based only on a sample of our population