Research Methods

Essay text:

- 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