Presentation Transcript
Experimental Designs: Experimental Designs Chee-Wee Tan P1112
Different Types of Methods: Different Types of Methods Research designs are like house blue-prints
Designs:
Observational
Quasi-experimental
Experimental
Observational Method: Observational Method Obviously, observing!
Example: Back pain observation
Disadvantages:
Long periods of observation
No cause-effect information
Terminology: Terminology 2 types of variables:
Independent
Dependent
Experimental Designs: Experimental Designs Cause & Effect
Difference between experimental & quasi-experimental?
Experimental
Controlled manipulation of independent variable
Quasi-experimental
Incomplete control of
independent variable
Quasi-experimental design: Quasi-experimental design Issues in quasi-experimental design
Handwashing example
Problems with experimental design
In some cases, ethical or practical considerations
Quasi-experimental
Provides alternative
Types of quasi-experimental design: Types of quasi-experimental design One group post-test design
One group pre-test/post-test design
Interrupted time series design One group post-test design
Types of quasi-experimental design: Types of quasi-experimental design
Experimental designs: Experimental designs 2 types of experimental designs
Between groups / independent measures
Repeated measures / within subjects ???
Randomisation: Randomisation Placing participants randomly into the groups
Purpose: prevent our own bias in influencing allocation Do stats and prosper! I love stats
Between group designs: Between group designs Different groups of participants for different conditions
Advantages:
Simple
Practice and fatigue not a problem
Between group designs: Between group designs Disadvantages:
More tedious
Less sensitive to detect any experimental effects
Examples of between group designs: Examples of between group designs
Post-test only / control group design
Pre-test / post-test control group
Repeated Measures: Repeated Measures Participants allocated to all conditions
Advantages:
More economical
More sensitive in detecting effects
Disadvantages:
‘Carry over’ effect
Intervention must be reversible
More designs: More designs Multiple levels of the independent variable designs
Multi-factorial designs
Latin square designs
Multivariate designs
Single-subject experimental designs
Why are research designs important?: Why are research designs important? Exclude unknown factors
Makes it easier for interpretation
A warrior knows his research designs as intimately as his own weapon……..Grrrrrr Me!