The experimental research where cause meets effect
Experimental Research: Where cause meets effect
Characteristics of an experiment• IV is the variable selected and tested by the researcher to assess effects on the DV (i.e participants responses)• It is assumed that changes in the DV will result after exposure to the IV.• IV and potential unwanted variables (e.g extranious variables) are controlled• Use of random allocation of participants to different conditions (groups) ensures uniform distributed participant characteristics that can affect the DV.
VariablesIndependent variable – the variable that is changed by the experimenter, interested in its effect. We want to see the effect of the IV on the DV Dependent Variable – measures the effect of the IV, see if the IV has effected the DV
Experimental group and Control groupExperimental group: Participantsexposed to the treatment condition, i.ethe IV manipulation. Control group: Participants not exposed to the IV manipulation.
The Research HypothesisHypothesis – a testable prediction relating to the outcome of theresearch being conducted, a prediction that one variable (IV) willeffect another variable (DV) in a certain way.
ExampleResearch Question: Does smoking marijuana effect drivingperformance? Independent Variable - smoking marijuana Dependent Variable - driving performanceIt is hypothesised that participants who smoke marijuanawill perform worse on a driving test as compared toparticipants who have not smoked marijuana
The Operational HypothesisVariables that need to be operationalisedSmoking MarijuanaDriving PerformanceThe population – who we are testingOperational DefinitionsSmoking Marijuana – smoking one joint containing 500milligrams of pure marijuana (not mixed with tobacco) 20minutes before taking a driving testDriving Performance -% score on VIC Roads, “Are you RoadReady?”driving simulatorPopulation - Victorian drivers aged 18 – 25
The Operational HypothesisIt is hypothesized that Victorian drivers aged 18 – 25 whohave smoked marijuana (smoking one joint containing500 milligrams of pure marijuana 20 minutes beforetaking a driving test) will perform worse on a driving test(obtain a lower % score on the VIC Roads “Are you RoadReady?” driving simulator) compared to participants whohave not smoked marijuana.
Extraneous and Confounding VariablesExtraneous Variable: Any variable, other than the IV, that cancause a change in the DV and therefore affect the results of anexperiment in an unwanted way. An extraneous variable maybecome a confounding variable. Confounding variable: Any variable, other than the IV, that is uncontrolled and allowed to change together with the IV, thereby having an unwanted effect on the DV