Experiments & Quasi Experiments

Question 1

Experiments

Answer 1

An experiment is when the researcher deliberately manipulates the independent variable to see the effects on the dependent variable

When we conduct an experiment we compare the results of one condition of the experiment with the results of another condition - the conditions of the experiment are the different levels of the IV
An experiment normally takes place in a controlled environment, but sometimes takes place in a real life condition

Question 2

Advantages

Answer 2

Because the researcher manipulates the independent variable under controlled conditions you can assume cause and effect

You can control extraneous variables more easily and therefore this results in greater internal validity

Takes place in a real life setting so participants are likely to behave normally increasing the ecological validity

Question 3

Disadvantages

Answer 3

Experiments can take place in a controlled environment which can be a bit artificial
Therefore participants may behave unnaturally- this will result in low ecological validity

Often more ethical issues than other methods - e.g. observations, surveys

In a real life setting it is difficult to control for confounding variables- so therefore the internal validity is lower than in a lab

Question 4

Quasi Experiment

Answer 4

A quasi experiment is not a true experiment because the IV has not been deliberately manipulated to see the changes in the DV, however the IV may change naturally

You would use a quasi experiment when it would be unethical to manipulate the IV, or if you were not able to manipulate the IV as it is not a true variable

In a quasi experiment the participants are not randomly assigned, unlike the real experiment, instead the participants will be placed in a group
There is also no control group in a quasi experiment

Question 5

Two Types of Quasi Experiment

Answer 5

Natural Experiment:
- This is when it is not possible or practical to manipulate the IV
- E.G. effects of watching violence on TV, how stress affects people

Different Studies:
- This is a type of quasi experiment where the IV is not something that varies at all - it is a condition that exists
- E.G. hypothesis that look for differences in gender on for example aggression, or differences in age on performance

Question 6

Advantages

Answer 6

Allows research where it would be useful unethical or not practical to manipulate the IV
For Example violence on TV

Enables researchers to study real problems such as the effects of stress on health

More likely to be realistic and therefore ecologically valid

Question 7

Disadvantages

Answer 7

Because you are not directly changing the IV you cannot assume the IV was responsible for causing any change in the DV

This is because there may be other variables present that may also cause the DV to change

For Example - if you studied the effect on stress on heart disease- it maybe that people who are stressed have unhealthy lifestyles that cause heart problems rather than stress