PY4 - EXPERIMENTAL METHODS - QUASI EXPERIMENTS

Question 1

What is a quasi-experiment?

Answer 1

A quasi-experiment is often described as studies that are ‘almost’ experiments. It is an experimental method in which the experimenter has not manipulated the independent variable directly as the independent variable would vary whether or not the researcher was interested. The researcher will record the effect of the independent variable on a dependent variable and this may be measured in a lab. As a quasi-experiment does not involve the deliberate manipulation of the independent variable or random allocation of participants, causal conclusions can only be tentatively drawn.

Question 2

What are the strengths of a quasi-experiment?

Answer 2

• One strength is its high external validity. As the independent variable is one that comes from real life and hasn’t been created deliberately by the researchers, they are more likely to be able to generalise the results to other real life groups and situations.

Question 3

What are the weaknesses of a quasi-experiment?

Answer 3

• One weakness of a quasi experiment is its lack of control over the independent variable. As a result, the researcher cannot say for certain that any change in the dependent variable was caused by the independent variable. For instance, if there were uncontrolled confounding variables then observed changes in the dependent variable might not be due to the independent variable. These variables can lower the internal validity of the experiment and for this reason, cause-and-effect conclusions from quasi experiments will always be a bit more tentative as you cannot be so confident about accepting or rejecting the null hypothesis.
• Additionally, random allocation of participants is not possible in a quasi experiment. Therefore, there may be biases in the different groups of participants. As participants are not randomly assigned, quasi-experimental research also does not eliminate the problem of confounding variables. Importantly, the biases that may occur in quasi-experimental studies may lead to a loss of internal validity, limiting the study’s ability to confidently conclude causal relationships between the independent and dependent variable.
• As well as this, quasi experiments can be described as often having low population validity as the possible unique characteristics of the sample mean that the findings cannot be generalised to other groups of people.