Lesson 1 research methods (variables & hypothesis)
1. Experimental Research: Where cause meets effect
Lesson 1:
Research
Methods
(Variables and
Hypothesising)
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2. Objectives: Lesson 1
Outline the scientific method in
psychological research
• Identify variables including the
dependent, independent, extraneous
and confounding variables
• Construct a research and
operational hypothesis of a research
question
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3. 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.
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4. Variables
Independent 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
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5. Activity:
Research Question:
Does drinking alcohol effect driving?
Identify the IV and DV
Write a research hypothesis
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6. Experimental group and Control group
Experimental group: Participants
exposed to the treatment condition, i.e
the IV manipulation.
Control group: Participants not
exposed to the IV manipulation.
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7. The Research Hypothesis
Hypothesis – a testable prediction relating to the outcome of the
research being conducted, a prediction that one variable (IV) will
effect another variable (DV) in a certain way.
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8. Example
Research Question: Does smoking marijuana effect driving
performance?
Independent Variable - smoking marijuana
Dependent Variable - driving performance
It was hypothesised that participants who smoke marijuana
will perform worse on a driving test as compared to
participants who have not smoked marijuana
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9. Operationalisation of Variables
Variables that need to be operationalised
Smoking Marijuana
Driving Performance
The population – who we are testing
Operational Definitions
Smoking Marijuana – smoking one joint containing 500
milligrams of pure marijuana (not mixed with tobacco) 20
minutes before taking a driving test
Driving Performance -% score on VIC Roads, “Are you Road
Ready?”driving simulator
Population - Victorian drivers aged 18 – 25
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10. The Operational Hypothesis
It was hypothesised that Victorian drivers aged 18 – 25 who
have smoked marijuana (smoking one joint containing
500 milligrams of pure marijuana 20 minutes before
taking a driving test) will perform worse on a driving test
(obtain a lower % score on the VIC Roads “Are you Road
Ready?” driving simulator) compared to participants who
have not smoked marijuana.
Note: Not required according to VCAA - however you do
need to be able to operationalise the variables!!
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11. Activity:
Research Question:
Does drinking red cordial
make children
hyperactive?
Operationalise the
independent and
dependent variables
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12. Extraneous and Confounding Variables
Extraneous Variable: Any variable, other than the IV, that can
cause a change in the DV and therefore affect the results of an
experiment in an unwanted way. An extraneous variable may
become 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
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14. Activity:
1)Identify one extraneous variable.
2)Identify an ethical breach in the
experiment.
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15. Revision
Do drivers who have more experience behind the wheel have less
accidents than less experienced drivers?
IV =
DV =
EV =
Research Hypothesis:
Operationalised Variables:
IV:
DV:
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