1. Experimental Research: Where cause meets effect
Lesson 1:
Research
Methods
(Variables and
Hypothesising)
Friday, 11 January 2013

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
Friday, 11 January 2013

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.
Friday, 11 January 2013

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
Friday, 11 January 2013

5. Activity:
Research Question:
Does drinking alcohol effect driving?
Identify the IV and DV
Write a research hypothesis
Friday, 11 January 2013

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.
Friday, 11 January 2013

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.
Friday, 11 January 2013

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
Friday, 11 January 2013

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
Friday, 11 January 2013

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!!
Friday, 11 January 2013

11. Activity:
Research Question:
Does drinking red cordial
make children
hyperactive?
Operationalise the
independent and
dependent variables
Friday, 11 January 2013

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
Friday, 11 January 2013

13. Watch Clip Below Summary
Friday, 11 January 2013

14. Activity:
1)Identify one extraneous variable.
2)Identify an ethical breach in the
experiment.
Friday, 11 January 2013

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:
Friday, 11 January 2013