- factor or characteristic set by the researcher that is being investigates as a possible cause of a change in behaviour
- CAUSE
Dependent Variables
- factor or characteristic being measures that is thought to be affected by a change in the value of the IV
- EFFECT
Population
- complete set of individuals/participants under consideration from which a sample may be drawn
Sample
- subset of the population under investigation
Random Sample
- everyone in population has equal chance of being selected
- avoids bias
Random Stratified Sample
- used when researchers are interested in identifying characteristics that vary between groups of people in the population
- divide population into strata and then sample randomly from each strata
Opportunity Sample
- Participants selected from groups and regions that are readily available
- convenience sample
- has bias
Experimental Group
- exposed to treatment (IV present)
Control Group
- exposed to control condition (IV absent)
- provides a point of reference with which to compare experimental group
Random Allocation
- procedure for assigning participants to various groups in an experiment
- all participants have an equal chance of being allocated to either control or experimental group
- used to ensure participants in experimental group are similar to those in the control group
Placebo and Experimenter Effects
Placebo Effect
- participant expectation
- change in behaviour caused by the belief that one has taken a drug
- single blind procedure ? participants do not know if they are in experimental or control group
Experimenter Effect
- changes in participants behaviour that are caused by the unintended influence of an experimenter
- experiment finds what it expects to
- Double blind procedure ? neither the participant or the experimenter know what group the person is
Research Designs
Experimental Design
- process of organising and structuring an experiment
Extraneous Variables
- any potential IV that is of no direct interest to the researcher, but may have an effect on the DV
Repeated Measures
- participants take part in both experimental and control conditions
- each participant is repeatedly tested
- positive - no individual differences between participants in each condition, need less participants
- negative ? may have order effects, effects of the first condition, may artificially affect the scores of the next condition
Matched Participants
- researcher attempts to mimic to repeated measures design but different participants are tested in each experimental condition
- to minimise participant variables, participants are matched on these variables in an attempt to remove their influence
- match participants on a variable and then randomly assign them to experimental or control group
- positive ? person only receives on condition so nor order effect
- controls for important extraneous variables
- negative ? more participants needed may still be other variables that you have not thought of which effects results
Independent Groups
- researcher randomly allocates each participant to treatment condition
- weakest of all reducing effect of individual (participants) differences between conditions
- easy to do displayed 300 characters
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- factor or characteristic set by the researcher that is being investigates as a possible cause of a change in behaviour
- CAUSE
Dependent Variables
- factor or characteristic being measures that is thought to be affected by a change in the value of the IV
- EFFECT
Population
- complete set of individuals/participants under consideration from which a sample may be drawn
Sample
- subset of the population under investigation
Random Sample
- everyone in population has equal chance of being selected
- avoids bias
Random Stratified Sample
- used when researchers are interested in identifying characteristics that vary between groups of people in the population
- divide population into strata and then sample randomly from each strata
Opportunity Sample
- Participants selected from groups and regions that are readily available
- convenience sample
- has bias
Experimental Group
- exposed to treatment (IV present)
Control Group
- exposed to control condition (IV absent)
- provides a point of reference with which to compare experimental group
Random Allocation
- procedure for assigning participants to various groups in an experiment
- all participants have an equal chance of being allocated to either control or experimental group
- used to ensure participants in experimental group are similar to those in the control group
Placebo and Experimenter Effects
Placebo Effect
- participant expectation
- change in behaviour caused by the belief that one has taken a drug
- single blind procedure ? participants do not know if they are in experimental or control group
Experimenter Effect
- changes in participants behaviour that are caused by the unintended influence of an experimenter
- experiment finds what it expects to
- Double blind procedure ? neither the participant or the experimenter know what group the person is
Research Designs
Experimental Design
- process of organising and structuring an experiment
Extraneous Variables
- any potential IV that is of no direct interest to the researcher, but may have an effect on the DV
Repeated Measures
- participants take part in both experimental and control conditions
- each participant is repeatedly tested
- positive - no individual differences between participants in each condition, need less participants
- negative ? may have order effects, effects of the first condition, may artificially affect the scores of the next condition
Matched Participants
- researcher attempts to mimic to repeated measures design but different participants are tested in each experimental condition
- to minimise participant variables, participants are matched on these variables in an attempt to remove their influence
- match participants on a variable and then randomly assign them to experimental or control group
- positive ? person only receives on condition so nor order effect
- controls for important extraneous variables
- negative ? more participants needed may still be other variables that you have not thought of which effects results
Independent Groups
- researcher randomly allocates each participant to treatment condition
- weakest of all reducing effect of individual (participants) differences between conditions
- easy to do displayed 300 characters
