Research Methods Flashcards
Independent variable (IV)
- In experiments
- Manipulated by the experimenter in order to observe effects on dependent variable
- E.g. what are the two conditions of the experiment? - male or female
- This is used to establish cause and effect
- The one that is CHANGED
Dependent variable (DV)
- In experiments
- The DV depends in some way and the IV
- How the effect of the change in the IV is measured
- E.g. different scores, different times
- The one that is MEASURED
Co-variables
- In correlations
- When using a correlation, it is impossible to directly manipulate the variables
- In this circumstance we would have to measure two separate variables and then compare them to each other
Operationalisation
Making something measurable
Examples of operationalisation of variables
1 - stating the method of measuring the DV
DV is time = not operationalised
DV is time takes to do task in seconds = operationalised
2 - Using a questionnaire to measure happiness
Extraneous variables
Any variables that might affect the DV so we try to keep them the same to ensure a fair test
Confounding variables
Variables which have not been kept the same (controlled) so may have affected the DV
Experiments
Involve manipulation of an independent variable to measure the effect on a dependent variable. There are 4 types of experiment.
Lab experiment
- IV is directly controlled by the experimenter
- Takes place in tightly controlled, artificial situations
Strengths of lab experiments
- Easy to replicate
- High internal validity due to good control of variables
- Can establish cause and effect
Limitations of lab experiments
- Lacks ecological validity as tasks are more artificial
- Participants may try to guess the aim of the study
An example of a lab experiment
Lotus and Palmer
Field experiment
- IV is deliberately manipulated by the researcher
- A controlled experiment
- It is conducted in a more “ordinary” environment
- The “field” is anywhere outside of the laboratory
Strengths of field experiments
- Participants are usually not aware they are participating in an experiment so behaviour may be more natural as they are not responding to demand characteristics
- Participants may be more relaxed
- Higher external validity due to greater mundane realism
Limitations of field experiments
- Lower internal validity (more difficult to control extraneous and confounding variables)
- Ethical issues as participants may not know they are being studied
Natural experiment
- Conducted when it is not possible, for ethical or practical reasons, to deliberately manipulate an IV
- The IV varies naturally and would vary whether or not the researcher was interested
Strength of natural experiments
- Enables psychologists to study “real” problems such as the effects of a disaster on health (mundane realism and ecological validity)
Limitations of natural experiments
- Cannot demonstrate causal relationships because IV is not directly manipulated
- Random allocation is not possible so confounding variables may impact internal validity
- Can only be used where conditions vary naturally
Quasi experiment
- Studies that are “almost” experiments
- IV is actually not something that varies at all - it is just a condition that exists e.g. age and gender
Strength of quasi experiments
- Allows comparisons between types of people
Limitations of quasi experiments
- Participants may be aware of being studied, creating demand characteristics and reducing internal validity
- Dependent variable may be a fairly artificial task, reducing mundane realism
Example of a field experiment
Bickman (IV - what they were wearing (dressed as a milkman, security guard and ordinary clothes) DV - obedience)
Example of a natural experiment
Effects of institutionalisation in Romanian orphanages
Rutter (IV - age of adoption, DV - IQ)
Example of a quasi experiment
Miller (1956)
How age affects short-term memory (digit span test)