Research methods

Qualitative research focuses on a participant’s thoughts and feelings about a situation.

Strength – rich and detailed with high ecological validity

Weakness – difficult to replicate and low reliability as it’s subjective.

Quantitative research focuses on measuring behaviour in a numerical way.

Strength – can replicate and more objective.

Weakness – less meaningful and low in ecological validity.


Random sampling is where every member of the target population has an equal chance of being chosen for the sample. This can be done by drawing names from a hat or using a computer generator.

Strength – more likely to be representative.

Weakness – time consuming.


Systematic sampling is where every nth member of the target population is chosen.

Strength – simple procedure and avoids research bias.

Weakness – sample may not actually be representative.


Stratified sampling is where the researcher identifies the subgroups of the target population and draws participants from each one.

Strength – represents target population well.

Weakness – very time consuming.


Opportunity sampling is where the sample consists of people who are able to take part.

Strength – quick and easy.

Weakness – unlikely to be represent target population.


The independent variable is the variable the researcher changes or manipulates.

The dependent variable is the variable the researcher is measuring (always some aspect of behaviour).


Laboratory experiment is a carefully controlled environment.

Strength – high validity and ethical as participants know they’re taking part.

Weakness – artificial situation so less ecologically valid.


Field experiment is an experiment held in a natural environment.

Strength – very high ecological validity.

Weakness – less ethical as participants might not always know that they’re taking part.


Quasi experiment is where there is no random allocation and thus no controlled manipulation of IV.

Strength – allows an investigation using pre-existing variables.

Weakness – no direct manipulation so less confidence in inferring cause and effect.

Extraneous variable is a variable other than the IV which may affect the DV if not controlled.


Participant variables occur when individual characteristics of participants affect their behaviour in an experiment.


Situational variables occur when the environment has different conditions in experiments.


Experimenter variables occur when the


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