Single-Subject
(Small-n) Designs
These designs
are common in clinical research and avoid the necessity of inferential
statistics
Main
Types:
1) Baseline Designs
2) Discrete Trials Designs
Baseline
Designs
These designs have at
least one baseline period, and at least one
intervention period.
Functions
of the Baseline:
1) Establishes the level
of the DV prior to intervention
2) Allows the assessment
of variability in DV (Can invovle applying a stability criterion)
Assessing
Reliability
Intrasubject Replication:
e.g., ABAB designs,
insure effect (that is
confounded by time) is replicable
Assessing
Generalizabiliy
Intersubject Replication
Present data from each
subject individually
Variation
in baseline
Variability can be due
to:
1) chance variation
2) carryover effects
Problematic
baselines:
· Drifting baselines
· Unrecoverable
baselines (due to carryover effects)
· Unequal baselines
between subjects
· Inappropriate
baselines -- floor and ceiling effects
Terminology:
· Single-factor
(e.g., AB, ABA, ABAB)
· Multi-factor
designs (> 1 IV)
· Multiple baseline
design (>1 DV)