Lesson 1 - Experimental Methods

Question 1

Indepedent Variable (IV)

Answer 1

Variable that the researcher manipulates in order to determine its effect on the dependent variable
May be divided into levels, sometimes referred to as experimental conditions
To provide a standard against which experimental conditions can be compared to, there may be a control condition where the IV is not manipulated at all

Question 2

Dependent Variable (DV)

Answer 2

Variable that is being measured

IV and DV should be operationalised

Question 3

Operationalisation

Answer 3

Defining the variables in such a way to make them measurable

Question 4

Extraneous Variables (EV)

Answer 4

These are any variables (excluding the IV) that COULD affect the DV

Question 5

Cofounding Variables (CV)

Answer 5

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

Question 6

Laboratory Experiments

Answer 6

Carried out in a controlled environment, allowing researcher to exert high level of control over IV and elimate any EV
Researcher then measures change in DV caused by manipulation of IV
Participants are randomly allocated to a condition
This means neither the experimenter nor participant decide which condition the participant is placed in - increased validity

Question 7

Laborary Experiments Advantages

Answer 7

High level of control possible in a lab means that it is easy to control for any EV and prevent them from being CV
As the researcher can manipulate the IV, they can establush a cause and effect relationship between the IV and DV
Well-controlled lab experiments can be easily replicated to see if similar resutls are obtained. If findings are similar, results are reliable

Question 8

Laborary Experiments Disadvantages

Answer 8

Strong chance of demand characteristics, type of EV where participants guess what the experiment is about and so alter their behaviour
Establishing a high level of control leads to lack of mundane realism and ecological validity

Question 9

Field Experiments

Answer 9

Carried out in the real world

IV is manipulated by the researcher to see the effect on the DV

Question 10

Field Experiments Advantages

Answer 10

Increased mundane realism and ecological validity compared to a laboratory experiment
Cause and effect relationship between IV and DV can be established as IV can be manipulated
Less chance of demand characteristics as participants may not be aware they are taking part in research

Question 11

Field Experiments Disadvantages

Answer 11

Much less control over EV so effect on DV may not be caused by IV. Means research is not valid
Less control over sample
May be far more difficult to replicate

Question 12

Natural Experiments

Answer 12

The researcher takes advantage of a naturally occuring IV to see its effect on the DV

Question 13

Natural Experiments Advantages

Answer 13

High level of mundane realism and ecological validity

Useful when it is impossible or unethical to manipulate the IV/sample in a lab or field experiment

Question 14

Natural Experiments Disadvantages

Answer 14

Less control over EV
Difficult to replicate
Difficult to determine cause and effect

Question 15

Quasi Experiments

Answer 15

Contain a naturally occuring IV
Naturally occuring IV is a difference between people that already exists
Researcher examines effect of this variable on the DV

Question 16

Quasi Experiments Advantages

Answer 16

High level of control

Easy to replicate

Question 17

Quasi Experiments Disadvantages

Answer 17

Lacks mundane realism and ecological validity

High chance of demand characteristics