Lesson 1- Experimental Methods

Question 1

The independent variable (IV)

Answer 1

This is the variable that the researcher manipulates in order to determine the effect on the dependent variable.

The IV may be divided into levels, sometimes referred to as experimental conditions.

To provide a standard against which experimental conditions can be compared there may be a control condition where the IV is not manipulated at all.

Question 2

The dependent variable (DV)

Answer 2

This is the variable that is being measured

Question 3

Extraneous variables (EV)

Answer 3

These are any variables other than the IV that COULD affect the DV

Question 4

Confounding variables (CV)

Answer 4

These are any variables (other than the IV) that HAVE affected the DV

Question 5

Laboratory experiments

Answer 5

This is when an experiment is carried out in a controlled environment, such as laboratory,

Allows the researcher to exert a high level of control over the IV and eliminate any EV

The researcher can then observe and measure the change in the DV caused by their manipulation of the IV.

Participants are usually randomly selected to a condition- this means neither the experimenter nor the participants decided which condition the participant is placed in, an unpredictable method

Question 6

Advantages of lab experiment

Answer 6

1. The high level of control paeans that it is easy to control for any EV and prevent them from becoming CV.
2. Researcher can manipulate the IV they can establish a cause and effect relationship between the IV and the DV
3. can be easily replicated by other researchers to see if similar results can be obtained. If the findings are similar to the original study than the results are reliable

Question 7

Disadvantages of lab experiments

Answer 7

1. Strong chance of demand characteristics with a lab experiment (a type of EV where participants guess what the experiment is about and alter their behaviour)
2. Lack of mundane realism because high level of control is established over the IV and extraneous variables. This means the the study does not have ecological validity

Question 8

Field experiment

Answer 8

This is an experiment carried out in the real world or in a natural setting, such as a classroom, rather than in the artificial setting of a lab

The IV is still manipulated or controlled by the researcher to see the effect of the DV

Question 9

Advantages of field experiment

Answer 9

1. More mundane realism and ecological validity than in a lab
2. Because the researcher can manipulate the IV, a cause and effect relationship between the IV and the DV can be established
3. Less chance of demand characteristics (participants might not even be aware that they are taking part in research, therefore act naturally)

Question 10

Disadvantages of field experiment

Answer 10

1. Much less control over EV and so the effect on the DV may not be caused by the IV but by these EV. this means the research is not valid (not measuring what it intends to measure;
2. There is a less control over the sample
3. Field experiments may be far more difficult to replicate

Question 11

Quasi experiment

Answer 11

Occurs when the researcher is not able to randomly allocate participants to different conditions of the experiment.

This is usually because the IV is a quality of the participant

Eg) comparing adults to children or males to females

Question 12

Natural experiments

Answer 12

For this type of experiment the researcher takes advantage of a naturally occurring IV to see the effect on the DV

Question 13

Advantages of natural experiment

Answer 13

1. There is a high level of mundane realism and ecological validity
2. Useful when it is impossible or unethical to manipulate the IV in a lab or field experiment

Question 14

Disadvantages of natural experiment

Answer 14

1. Less control over EV
2. Difficult to replicate
3. Far more difficult to determine cause and effect