Single Subject
description
Transcript of Single Subject
Single Subject
Jesus Valdez
Purpose
To study the changes in behavior of an individual exhibits after exposure to an intervention or treatment of some sort.
Essential characteristics
Line graphs Dependent outcome is expressed on y-axis Sequence of time is expressed on x- axis Involves extensive collection on subject Can be applied where group designs are
difficult
2 ways it differs from other forms of research
1. Baseline is followed by the independent variable
2. Figure caption near the bottom of the graph
What is and why baseline
What?
Graphic record of measurements taken prior to introducing an intervention in a time-series design
Why?
It’s the control before the treatment
The 6 Designs
A-B Reversal (A-B-A) A-B-A-B B-A-B A-B-C-B Multiple-baseline
A-B Design
Design in which measurements are repeatedly made until stability is presumably established (baseline), after which treatment is introduced and an appropriate number or measurements are made
A-B-A Design
Same as A-B design, except a second baseline is added
A-B-A-B Design
Same as A-B-A design, except a second treatment is added
B-A-B Design
Same as A-B-A-B design, except the initial baseline phase is omitted
A-B-C-A Design
Same as A-B-A design, except a second baseline phase is replaced by a modified treatment phase
Multiple-Baseline Design
Experimental design in which baseline data are collected on several behaviors for on subject, after which the treatment is applied sequentially over a period of time to each behavior
Threats to internal validity
Length of the baseline and conditions Number of variables changed form condition
to condition Degree and speed of change Return or not of baseline levels Number of baselines
Ways to control threat
Subject characteristics, mortality, testing, and history
Less effective with location, date collector characteristics
Weak in instrument decay, data collector bias, attitude
External validity
Are weak when it comes to generalizability Important to replicate to test generalization
Example of Single Subject
Onto the Internet