Research methods: sampling, ethics and data

Sampling

• The target population is the group a study is about; a sample is the people who take part.
• Random sampling: everyone has an equal chance of being chosen. Opportunity sampling: whoever is available. Systematic sampling: every nth person. Stratified sampling: subgroups are represented in proportion.
• A representative sample allows findings to be generalised to the target population.

Ethics

• Researchers should gain informed consent, avoid deception where possible, protect participants from harm, keep data confidential, allow the right to withdraw, and debrief participants afterwards.

Data and analysis

• Quantitative data is numerical; qualitative data is descriptive. Primary data is collected by the researcher; secondary data already exists.
• Measures of central tendency: mean (add up and divide by the number of scores), median (the middle value) and mode (the most common value). Range is a measure of spread: the highest minus the lowest.
• Correlations can be positive (both variables rise together), negative (one rises as the other falls) or show no correlation. They are shown on scatter diagrams, and don't prove cause and effect.
• Reliability: consistency of results. Validity: whether a study measures what it claims to.

Key terms

Target population

The group a study is about.

Random sampling

Everyone has an equal chance of being chosen.

Opportunity sampling

Using whoever is available.

Informed consent

Agreeing to take part knowing what the study involves.

Debriefing

Telling participants the full aims after the study.

Mean

The total of the scores divided by the number of scores.

Median

The middle value when scores are in order.

Correlation

A relationship between two variables.