lesson 1 research methods (variables & hypothesis)

Experimental Research: Where cause meets effect

Lesson 1:Research Methods

(Variables and Hypothesising)

Friday, 11 January 2013

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


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.


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


Activity:

Research Question: Does drinking alcohol effect driving?

Identify the IV and DV Write a research hypothesis


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.


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.


Example Research Question: Does smoking marijuana effect 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

Independent Variable -

Dependent Variable -

smoking marijuana

driving performance


Variables that need to be operationalised Smoking MarijuanaDriving PerformanceThe population – who we are testing

Operationalisation of Variables

Smoking Marijuana – smoking one joint containing 500 milligrams of pure marijuana (not mixed with tobacco) 20 minutes before taking a driving test

Operational Definitions

Driving Performance -% score on VIC Roads, “Are you Road Ready?”driving simulator

Population - Victorian drivers aged 18 – 25


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!!


Activity:

Research Question: Does drinking red cordial

make children hyperactive?

Operationalise the independent and

dependent variables


Extraneous and Confounding Variables

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

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.


Watch Clip Below Summary


Activity:

1)Identify one extraneous variable.2)Identify an ethical breach in the

experiment.


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:


lesson 1 research methods (variables & hypothesis)

Documents

variable iv

variable dv

dvdependent variable

variablesindependent

iv manipulation

experiment iv

withthe iv

marijuana effect