Quasi Experiment vs. True Experiment

Attribute	Quasi Experiment	True Experiment
Random assignment	No	Yes
Control over variables	Less control	More control
Cause and effect relationship	Weaker	Stronger
Pre-existing groups	Used	Not used
Random selection	No	Yes

Definition

A quasi experiment is a type of research design that shares similarities with true experiments but lacks the element of random assignment to treatment or control groups. This means that participants are not randomly assigned to groups, which can introduce bias into the results. On the other hand, a true experiment is a research design where participants are randomly assigned to either a treatment or control group, allowing researchers to draw more definitive conclusions about the effects of the treatment.

Control

In a true experiment, researchers have more control over the variables that may influence the outcome of the study. This is because participants are randomly assigned to groups, which helps to minimize the impact of confounding variables. In contrast, quasi experiments have less control over these variables since participants are not randomly assigned. This lack of control can make it more difficult to determine causality between the treatment and the outcome.

Validity

True experiments are generally considered to have higher internal validity compared to quasi experiments. This is because random assignment helps to ensure that any differences between the treatment and control groups are due to the treatment itself, rather than other factors. Quasi experiments, on the other hand, may have lower internal validity due to the potential for confounding variables to influence the results. However, quasi experiments may still have good external validity if the results can be generalized to a larger population.

Ethical Considerations

Both quasi experiments and true experiments must adhere to ethical guidelines when conducting research involving human participants. This includes obtaining informed consent, protecting participant confidentiality, and minimizing any potential harm. However, true experiments may raise additional ethical concerns due to the random assignment of participants to groups. This can raise questions about fairness and the potential for unequal treatment. Quasi experiments may be seen as more ethical in this regard since participants are not randomly assigned.

Sample Size

Sample size is an important consideration in both quasi experiments and true experiments. A larger sample size generally leads to more reliable results and increased statistical power. In true experiments, researchers have more control over the sample size since they can randomly assign participants to groups. This allows for a more balanced distribution of participants. In quasi experiments, researchers may have less control over the sample size, which can impact the reliability of the results.

Generalizability

One of the key differences between quasi experiments and true experiments is the generalizability of the results. True experiments are often seen as more generalizable since random assignment helps to ensure that the results are not biased by external factors. This means that the findings of a true experiment are more likely to be applicable to a larger population. Quasi experiments, on the other hand, may have limited generalizability due to the lack of random assignment and potential for bias in the results.

Conclusion

In conclusion, both quasi experiments and true experiments have their own strengths and weaknesses. True experiments offer higher internal validity and more control over variables, while quasi experiments may have good external validity and be more ethical in certain situations. Researchers should carefully consider the research question and objectives when choosing between these two research designs to ensure that they are able to draw valid and reliable conclusions.