Research Methods: Sampling Approaches and Techniques

Flashcards reviewing core concepts of research sampling, including population, census, probability vs. non-probability approaches, specific sampling techniques, sample size notation, and response rates.

What is a census in research?

A method of collecting data from the entire population of the study rather than a sample.

Why is a census rarely conducted in research studies?

It is extremely time-consuming and very expensive to collect data from an entire population.

What is defined as a subset of the population used in research?

A sample.

What term refers to individual cases or entities within a population or sample?

Unit of analysis.

What defines a probability sampling approach?

An approach where every unit of a population has the exact same chance of being chosen as part of the sample.

In which main type of research is probability sampling most commonly used?

Quantitative research, such as when conducting surveys.

What defines a non-probability sampling approach?

An approach where not every unit in the population has the same chance of being selected for the study.

In which main type of research is non-probability sampling most commonly used?

Qualitative research, such as focus groups, observations, or one-on-one interviews.

How does simple random sampling work?

Every unit in the population has an equal chance of selection, such as pulling names out of a hat or using a random numbers table.

How does systematic random sampling work?

Participants are selected using a structured system, such as counting off ones, twos, and threes across a group.

Why do researchers use proportional stratified sampling?

To match the exact demographic proportions of the overall population in the sample and avoid over-representation.

What is cluster sampling?

A probability sampling technique where groups naturally appear in the population, such as existing neighborhoods, cities, states, or regions.

What is key informant or expert sampling in non-probability research?

Selecting specific individuals who meet strict expert criteria to participate or share access to a specialized group.

What is voluntary or availability sampling?

A non-probability technique where participants volunteer to participate, such as college students agreeing to complete a survey for bonus points.

What is snowball sampling?

A non-probability technique that starts with one or a few key individuals who share the study with others to reach hard-to-find populations.

How are population size and sample size represented mathematically in research?

Population size is represented by capital $N$ and sample size is represented by lower case $n$.

What is the definition of response rate in a research study?

The proportion or percentage of people who actually agree to participate in the study after being asked.

What range is generally considered a good response rate in research practice?

75% and above, up to 90%.

What response rate level is considered unacceptable in research and requires gathering more data?

Anything lower than 50%.