Developmental Designs

Purpose:

Uses age as a prime independent variable.

3 major designs

A. Cross-sectional designs

1.

Age Group

Five Year Olds	Ten Year Olds	Fifteen Year Olds
Sally Fred Sam Judy	Mike Amy Liz Nate	John Brian Nicole Peter

2.

BUT

3. Possible problem of cohort effects

Cohort =

B. Longitudinal designs

1.

Time of Measurement

1985	1990	1995
Mary Herman Ellen Joe	Mary Herman Ellen Joe	Mary Herman Ellen Joe

2.

BUT

3.

4.

5.

6.

7.

a.

b.

C. Cohort-Sequential designs

1.

Time of Measurement

1985	1990	1995
5 years old	10 years old 5 years old	15 years old 10 years old 5 years old

2.

3.

Bias in Experiments

I. Experimenter Bias

A.

1.

2.

Ways to control experimenter bias

A.

B.

C.

II. Subject Bias -

A. Hawthorne effect - in treatment group

1.

2.

B. John Henry effect - in control group

1.

2.

C. Good subject effect

1.

D. Evaluation apprehension

1.

III. Ways to Control Subject Bias

1.

2.

3.