Small N Designs

I. Research designs using small numbers of subjects.

II. When to use a small N design

1.

 

 

2.

 

 

3.

III. Logic of a Single Subject Design

A.

 

B.

IV. Criticisms of Large N designs

A.

B.

3 Necessary Elements

1.

e.g.

2.

 

e.g.

 

 

 

3.

 

 

e.g.

 

 

 

D. A-B design- simplest form of small N design

1. A = 1st experimental phase (baseline)

 

2. B = 2nd experimental phase (treatment)

 

 

3. But...

E. Withdrawal Design

1.

 

2. A-B-A design

a.

 

F. A-B-A-B design is even better!!

a.

 

 

b.

 

 

 

G. A-B-C-B designs

1.

e.g. autistics - reinforcing napkin wiping behavior

2. Treatment B phase

3. Treatment C phase

4.

Problems with Withdrawal Designs:

A.

B.

V. Multiple Baseline Designs

A.

 

 

B.

 

 

C. Treatment is begun at different times - 3 types

1.

 

 

e.g. physical therapy program to help brain injured people regain the ability to walk.

2.

e.g. autistics - program to reduce problem behaviors at dinner.

 

Take baseline measures of all these behaviors.

1st use treatment only on napkin wipes, and see if behavior changes

2nd add treatment to # times a knife and fork are used

3rd add treatment to # times food is thrown

4th add treatment to amount of food eaten

 

 

3.

 

e.g. autistics - program to reduce problem eating behavior is general

A.

 

B.

VI Alternating Treatments Design

A.

1.

2.

VII. Changing Criterion Designs

1.

2.

e.g. regular exercising at a certain level for overweight people

3.

4. Once reached, the criterion is made more stringent

e.g. DeLuca and Holborn (1992) - program to help overweight 11-year-old boys start exercising.

1.

 

2.

 

3.

 

 

VIII Criticisms of Single-Subject Designs

A.

B.

1.

 

2.

 

3.

 

C.

D.