Experimental Methods

What is a laboratory experiment?

An experiment conducted in a controlled environment where the researcher manipulated the independent variables and controls extraneous variables to measure the effect on the dependent variable.

Give two strengths of laboratory experiments

1. High control over variables → higher internal validity

2. Easier to replicate due to standardised procedures, improving reliability

What is a field experiment?

An experiment conducted in a natural environment where the researcher manipulates the independent variable, but has less control over extraneous variables

One strength & one weakness of field experiments

Strength: High ecological validity due to the natural setting

Weakness: Lower control over extraneous variables, which can reduce internal validity

What is a natural experiment?

An experiment where the independent variable occurs naturally with the researcher observing effects on dependent variable

Define a quasi experiment

An experiment where the independent variable is naturally occurring, not manipulated by the researcher e.g age, gender

What is internal validity?

Extent to which a study measures what it claims to measure, free from confounding variables. Like a true picture.

What is external validity?

The extent of which findings can be generalised to real life settings, other populations and different times etc

What is operationalisation?

Defining variables in a practical so they can be tested or manipulated

Define independent variable

The variable that is manipulated or changed by the researcher to observe its effect on the dependent variable

Define dependent variable

Variable that is measured to see how it is affected by changes in the independent variable

What are confounding variables?

Variables other than the IV that may affect the DV and results of experiment.

What is a hypothesis?

Precise, testable prediction about how one variable will effect the other

What is the difference between a directional & non-directional hypothesis

Difference between one-tailed predicts the direction of the effect; non-directional predicts a difference but not the direction