Week 2 Experimental designs

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Presentation Description

University: Queen Margaret University, Edinburgh Lecturer: Chee- Wee Tan Module: P1112

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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!