Definition of experimental method
Research method using random allocation of participants and the manipulation of variables to determine cause and effect
Definition of confounding variables
Uncontrolled extraneous variables that negatively affect results
Definition of demand characteristics
Features of research which allow participants to work out aim of study and change behaviour accordingly
Definition of investigator effects
Researcher effects where researchers features influence participants’ responses
Definition of lab experiment
Experiment conducted in controlled environment allowing establishment of causality
Definition of field experiment
Experement conducted in naturalistic environement where researchers manipulate the IV
Definition of quasi experiment
Experiment where researcher is unable to freely manipulate IV or randomly allocate participants to different conditions
Definition of behavioural catgories
Dividing target behaviours into subsets of behaviours through use of coding systems
Definition of self-report techniques
Participants giving info about themselves without researcher influence
Definition of questionaires
Self-report method where participants record their own answers to a pre-set list of questions
Definition of interviews
Self-report technique where participants answer questions in face-to-face situations
Why have a null hypothesis (one that predicts no effect)?
If results support null hypothesis, researchers origional idea might be incorrect. Whatever happens in stud, researcher needs to be able to accept a hypothesis at end of study
What’s a null hypothesis?
Hypothesis of no difference. Predicts IV won’t affect DV and that differences in results will be due to chance factors, not manipulation of IV and therefore no significant
What’s an experimental/alternative hypothesis?
Predicts that differences in DV will be beyond boundaries of chance (will occur as result of manipulation of IV)
What’s a non-directional hypothesis?
Predicts that there will be a difference but doesn’t predict direction of results
When is a directional hypothesis used?
When previous research suggests results will go in one direction or when replicating previous study that also used directional hypothesis
What’s ranodm sampling?
When each member of population has equal chance of being selected. Placing all names into a hat and draw required number of names/use random generator
Advantages of random sampling
Unbiased selection thus more likely representative
Results can be generalised
Disadvantages of random sampling
Impractical - time-consuming
Not representative - could all be females selected thus not representative and can’t be generalised
What’s opportunity sampling?
Selecting participants who are available and willing to take part. Ask people in street who are passing
Advantages of opportunistic sampling
Easy to carry out
Natural experiments - no contol over who is studied
Disadvantages of opportunistic sampling
Unrepresentative - easy to obtain biased sample by only using those around at the time
Self-selection - can refuse to take part
Advantages to volunteer sampling
Easy to do, little effort
Less chance of ‘screw you’ phenomenon as want to take part so less likely to sabotage
Disadvantages of volunteer sampling
Unrepresentative - biased so can’t be generalised
Demand characteristics - increases as egar to take part
What’s systematic sampling?
Taking every nth person from the list to take sample. Involves calculating size of population and assessing size of sample to calculate sampling interval