HLSC 2P27 Lec. 8 - Population Sampling

Target population

The general population that the study seeks to understand

source population

The specific individuals from which a representative sample will be drawn

Sample population

Individuals asked to participate

Study population

Eligible participants

Bias

Systematic error that can affect the study's design, conduct, or analysis, leading to incorrect results

Sampling bias

Happens when the sample is not representative of the source population

Nonrandom sampling bias

Happens when individuals do not have an equal chance of being selected for the study

Simple random sampling

Each person has equal chance of being selected

Systematic sampling

Every nth person is selected

Stratified sampling

Population is divided into groups with a common attribute and a random sample is chosen within each group

Cluster sampling

Population divided into clusters then some clusters are randomly selected

Goal of any sampling method

Create a sample population that represents the source population and ideally the target population

Participation rate

Percentage of the sample population included in the study

Internal validity

Extent to which the study design, conduct, and analysis answers the research question without bias

External validity

Extent to which the results of the study can be generalized to other settings, population, or times

Purposive Sampling

Non probability sampling method that recruits participants based on their unique insights

Data saturation

In qualitative research, when no new information emerges from further data collection

convenience sampling

where individuals are selected based on ease of access (eg., schools, workplaces, communities).