RM- Experiments Flashcards
Independent variable
What the researcher changes in an experiment
Dependent variable
What is being measured in the experiment
Control variable
What is kept the same during every measure in the experiment
Demand characteristics
When participants try to guess the aim of the study, leading to a change in their behaviour
Investigator effects
Any impact of the researchers behaviour on the results of the study (eg. Participant selection and experimental design)
Extraneous variables
Any variable other than the IV that affects the DV
Can be participant or situational
Confounding variables
Affects the two variables, making it seem like they have a cause and effect relationship
Participant variables
Individual differences between participants
Situational variables
Features of the environment that affect the DV
Random allocation
Each participant has an equal chance of being in each condition
Standardisation
Procedures and instructions are the same for all participants
Randomisation
The order of conditions and designs are decided by chance methods
Experimental designs
Independent groups
Repeated measures
Matched pairs
Repeated measures
All participants take part in all measures of the IV
Independent groups
Ps split into groups and each group does one measure of the IV
Matched pairs
Ps are paired using a variable relative to the experiment (eg. Age) and each do a different measure of the Iv. Their results are compared to each others
Evaluation of repeated pleasures
✅Controls individual differences
✅Needs fewer participants
❌Order effects
❌Demand characteristics
Evaluation of independent groups
✅No order effects
✅Less demand characteristics
❌Confounding and participant variables
❌Needs more participants
Evaluation of matched pairs
✅Controls participant variables
✅No order effects
❌Need more participants
❌Doesn’t account for other individual differences
Counter balancing
Addresses order effects
Some participants do condition A then B, others do B then A
This stops practice effects from influencing the results
Types of experiment
Laboratory
Field
Natural
Quasi
Lab experiment
In a highly controlled environment
IV is manipulated
Evaluation of lab experiment
✅High replicability
✅Limits extraneous variables
❌Low generalisability
❌Demand characteristics
Field experiment
In participants natural environment
IV is manipulated
Evaluation of field experiment
✅Limits demand characteristics
❌Harder to control
❌Ethical issues of consent
Natural experiment
Can occur in any setting
IV is not manipulated
Evaluation of natural experiment
✅High external validity
✅No harm caused if traumatic events are naturally occurring
❌Low reliability/standardisation
❌Participants cannot be allocated conditions - may be biased
Quasi experiment
Can occur in any setting
IV is naturally occurring like age or eye colour
Evaluation of quasi experiment
✅High ecological validity
✅Tests things which can’t be manipulated
❌Ps can’t be allocated conditions so may be biases
❌Can’t establish cause and effect
Pilot studies
A small scale version of an experiment
Tests for changes needed before the real study
Single blind procedure
Participant not told the true aims of the study to avoid demand characteristics (investigator effects may still exist)
Double blind procedure
Both researcher and participant not told true aims of the study to avoid demand characteristics and investigator effects
Control groups
Group that the participant group is compared to (eg. If testing drugs, they are given a placebo)
Definition of reliability
How consistent the findings from a study or measurement are
Ways to test reliability
Test retest reliability
Inter rater/observer reliability
Test retest reliability
The consistency of results of a test which is done on multiple occasions with the same participants
Inter rater/observer reliability
The consistency between two or more observers in the categorisation of behaviour
Ways to improve reliability
Give training to researchers/observers
Ensure clear criteria in an observation
Standardisation of procedure
Definition of validity
The extent to which the results of a test are true or accurate
Ecological validity
The extent to which findings can be applied from one setting to another (does it reflect real life?)
Temporal validity
The extent to which a study’s findings can be applied from one time period to another
Population validity
The extent to which findings of a study can be generalised to the target population (how well the sample reflects the target population.)
Internal validity
How well the test measures what it aimed to
External validity
How well the results can be applied to real life beyond the study
Target population
A group of people who the researcher wants to study
Sampling frame
A list of people in the target population who the sample will be picked from
Sample
The participants who take part in the research
4 sampling methods
Random
Opportunity
Stratified
Systematic
Volunteer
Random sampling
Each participant has an equal chance of being chosen
Evaluation of random sampling
✅ Avoids researcher bias
❌ Could be randomly biased
❌Participants could refuse to take part
Opportunity sampling
Choosing people who are readily available at the time of the study
Evaluation of opportunity sampling
✅Convenient
❌Possible researcher bias
❌Unrepresentative as the same people may be at the same place at a specific time
Volunteer/ self selected sampling
Study is advertised and participants sign up to do it
Evaluation of volunteer sampling
✅Convenient
✅Participants want to take part
❌May be unrepresentative (volunteer bias-attracting a certain profile of people)
Systematic sampling
Using the ordered sampling frame, pick every nth person to take part
Evaluation of systematic sampling
✅Diverse sample
✅No researcher bias
❌Requires sampling frame (effort)
❌Participants could refuse to take part
Stratified sampling
Subgroups identified in the target population. The proportion of subgroups in the population is matched in the sample
Evaluation of stratified sampling
✅Representative
✅Avoids researcher bias
❌Categories need to be defined
❌Requires sampling frame
❌Participants may refuse to take part
Definition of hypothesis
A precise and testable statement which stated the prediction of the variables being tested’s relationship
Directional hypothesis
States the exact relationship the variables will have
Also ‘one tailed’ hypothesis
Non directional hypothesis
Only states whether the variables will have a relationship, not what it will be
Also ‘two tailed’ hypothesis
Null hypothesis
States that the variables will be unrelated
Operationalisation
Definitions of the variables to enable behaviour to be measured objectively (eg. Measuring happiness from smiles)
