2.2.1-2.2.10 Experiments Flashcards
‘Experiment’ definition
A scientific procedure undertaken to test a hypothesis in order to demonstrate causal relationships
Outline what a ‘Lab Experiment’ is
-experiment where the researcher directly manipulates the IV to see the effect on the DV
-occurs in a controlled, artificial environment (control noise, space, temp)
-participants sign up
Outline what a ‘Field Experiment’ is
-experiment where the researcher directly manipulates the IV to see the effect on the DV
-occurs in a natural environment such as a school or a shopping centre
-experimenter goes to participants
Weaknesses of a Lab Experiment
-expensive to conduct
-participants are likely to guess aim and therefore demonstrate desired characteristics
-difficult to recruit participants
-time consuming to conduct
-low in external validity
Strengths of a Lab Experiment
-very scientific as it occurs in a controlled environment
-high repeatability and reliability as the same procedure is usually used for all participants
-participants can usually always give informed consent
-groups can be randomally allocated (no experimenter bias)
-high in internal validity (control of extraneous variables)
Weaknesses of a Field Experiment
-does not have full control over variables so not easy to repeat
-may not be able to gain informed consent
-sample could be unreppresentative
-low internal validity
Strengths of a Field Experiment
-shows natural behaviour but is also controlled
-high generalisability
-easy to gain participants
-participants won’t guess aim
-high in ecological validity
‘Hypothesis’ Definition
A statement that predicts the outcome of the results
‘Opeerationalisation’ Definition
Making the variable clear and precise by giving detail about the study
‘Experimental Group/Condition’ definition
The group who experiences the manipulated IV to see if it has any effect
‘Control Group/Condition’
the group that experiences no manipulation in IV, so it acts as a baseline for comparison
‘Experimental/Alternative Hypothesis’ definition
Hypothesis that states a relationship or difference between variables
‘Null Hypothesis’ definition
States that there is no relationship or difference between variables
‘Directional/One tailed Hypothesis’ definition
States the direction of the results thats expected (eg. higher, worse)
‘Non-Directional/Two Tailed Hypothesis’ definition
Does not predict the direction of results
‘Experimental Design’ definition
how participants are allocated to different groups in an experiment
‘Independent Measures’ definition
when different participants are used in each condition of the IV
Evaluate Independent Measures
Strengths: each participant takes part in 1 condition so therefore won’t guess the aim
Weaknesses: individual differences affect results, large group sizes are requires
‘Repeated Measures’ definition
when the same participants take part in each condition of the IV
Evaluate Repeated Measures
Strengths: eliminates individual differences, can have a small sample
Weaknesses: could guess the aim of research, could demonstrate order effects
‘Matched Pairs’ definition
pairs of participants are matched across groups in terms of key variables
Evaluate Matched Pairs
Strengths: overcomes individual differences
Weaknesses: difficult to find matched pairs, time consuming
‘Order Effects’ definition and examples
The effects or doing multiple trials in a repeated measures design eg. tiredness, practice
‘Counterbalancing’ definition
Steps that are taken to minimise the impact of order effects.
The participant sample is divided in half, with each half completing the two conditions in different orders
‘Random Allocation’ Definition
When participants are randomally allocated to the conditions in order to avoid bias and participant variables
‘Extraneous Variables’ definition
Variables that may affect results when they are not controlled for eg. alcohol consumption
‘Confounding Variables’ definition
Variables that impact the IV and DV as they aren’t controlled for eg. smoking
‘Participant Variables’ definition
Characteristics of those taking part eg. IQ
‘Situational Variables’ definition
Environmental factors that can affect the research
‘Experimenter Effects’ definition
Things about the experimenter that affect the results, rather than the change in IV
A weakness of matched pairs
eg. gender, age, clothing
‘Experimenter Bias’ definition
When the experimenter’s beliefs or aims interfere with the results
Resolved by using a 3rd party
‘Single Blind Trial’ definition
When the participant doesn’t know which group they’re in, but the researcher does
‘Double Blind Trial’ definition
when neither the experimenter or the participants know which group they’re in
‘Objectivity’ definition
A conclusion that’s based on scientific facts and observations that are provable and measurable
‘Subjectivity’ definition
A conclusion that’s affected by bias assumptions, beliefs and emotions
‘Reliability’ definition
The idea of consistency or replicability, results for a test should always be the same
‘Inter rater reliability’ definition
when two or more individuals have a high agreement on a score and therefore the measurement of behaviour is reliable
‘Test retest reliability’ definition
Testing multiple times to measure stability
‘Standardised Procedure’ definition
When the procedure is the same for every participant
‘Validity’ definition
whether a result is true and whether the investigation measures what it’s supposed to measure
‘Internal validity’ definition
a measure of whether results are affected only by changes to the IV
‘Construct Validity’ definition
Whether a measure successfully measures what it’s intended to
‘Concurrent Validity’ definition
extent to which the test correlates with a measure that’s been tested previously
‘Predictive Validity’ definition
If a test accurately predicts a future outcome
‘External Validity’ definition
a measure of whether the results can be generalised to situations outside of the one thag it’s measured in
‘Population Validity’ definition
Whether the results can be generalised to a larger population
‘Ecological Validity’ definition
Whether data is generalisable to the real world
‘Mundane Realism’ definition
How similar materials and procedures in an experiment are to real world events
‘Sampling’ definition
Process of selecting subjects to study from the target population, should be as representative as possible and of a sufficient size
‘Random Sampling’ definition
Participants are selected by chance, everyone has an equal chance of being selected, requires a method of numbering people
‘Opportunity Sampling’ definition
Researcher asks who is available at the time
‘Systematic sampling’ definition
Researcher divides target population into sections and takes an equal proportion from each group
‘Self selected’ definition
Participants take part because they volunteer, for example by responding to an advert
Evaluate ‘Random Sampling’
Strengths: represents target population, eliminates sample bias, can be representative
Weaknesses: time consuming, lots of effort, expensive, requires small groups
Evaluate ‘Opportunity Sampling’
Strengths: quick and easy, doesn’t require much time or effort
Weaknesses: not always reflective, experimenter bias
Evaluate ‘Volounteer Sampling’
Strengths: will comply with experiment, less work for experimenter, no experimenter bias
Weaknesses: not always representative as a certain type of person will volounteer
Evaluate ‘Stratified Sampling’
Strengths: highly representative, results can be generalised, can be done on small scale
Weaknesses: time consuming and difficult, rarely used, involves calculations and recruitment
