Stratified random sampling is a probability sampling method where a target population is first divided into distinct subgroups, known as strata, often based on demographic traits. After these groups are established, a simple random sample is drawn independently from each stratum, ensuring that various segments of the population are represented appropriately in the study.

Stratified Random Sampling

Simple random sampling is a method for obtaining a study sample where every single member of the target population has an equal chance of being selected. While this approach is effective for ensuring a representative sample, it is often difficult or impossible to achieve in psychological research because populations are rarely defined clearly enough to give everyone an equal selection chance.

Simple Random Sampling

The 1936 Literary Digest straw poll was a survey conducted to predict the outcome of the presidential election between Alf Landon and Franklin Roosevelt. The magazine attempted to forecast the results by sending ballots, which were also subscription requests, to millions of Americans. Based on this method, the editors incorrectly predicted that Landon would win in a landslide.

1936 Literary Digest Straw Poll

Which of the following provides the best definition of a sampling frame?

A sampling frame is essentially a comprehensive list of all members of a specified population from which a researcher will select respondents. Sources for these frames can include telephone directories, lists of registered voters, hospital records, or even geographic maps. Establishing an accurate sampling frame is a necessary prerequisite for conducting most forms of probability sampling.

Google

Probability sampling is a broad category of sampling methods where the researcher can mathematically specify the exact probability that each member of the defined population will be selected for the sample. Because it enables researchers to make highly accurate estimates about a population, it is the favored approach in survey research, though it requires a clear and precise specification of the target population before sampling begins.

Probability Sampling

In research, a population is the entire group of individuals that the researchers seek to draw conclusions about based on their findings from the sample. 

Population

https://kpu.pressbooks.pub/psychmethods4e/

KPU Research Methods in Psychology - 4th American Edition

Sampling Frame

Cluster sampling is a probability sampling technique where researchers randomly select larger groupings or 'clusters' of individuals—such as entire small towns or specific schools—and then randomly sample individuals from within those chosen clusters. This method minimizes travel and logistical costs for face-to-face interviews and is uniquely the only probability sampling approach that does not require a comprehensive sampling frame of the entire population.

Cluster Sampling

Which of the following is a key characteristic of probability sampling?

In research, the sample is studied with the goal of generalizing the results to the broader population from which the sample was drawn. This process allows researchers to make inferences about a large group based on data collected from a smaller, representative subset. The relationship is visually comparable to extracting a small representative group from a vast crowd.

Relationship Between Sample and Population

A team of educational psychologists wants to investigate the effectiveness of a new mathematics curriculum for all fourth-grade students in a particular country. To do this, they plan to implement the curriculum in 200 classrooms across various regions and measure the students' learning outcomes. In this research scenario, what is the population?

A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected. This method is often preferred for selecting experimental participants because, provided the sample is large enough, it provides reasonable assurance that the participating individuals are representative of the broader population.

Random Sample

Inferential statistics are a set of mathematical techniques used by researchers to determine whether a statistical result or relationship observed in a study's sample reflects something that is genuinely true of the broader population.

Learn Before

Related

Learn After