I.  Introduction

A. What is development?

B. The problem with studying change…

C. Developmental designs as Quasi-experimental designs

II.  Longitudinal Designs

A. Longitudinal designs allow us to

1.      observe change over time

2.      examine individual patterns (paths) 

3.      examine associations between past and present (stability) 

B. Problems with this design

C. So when is a longitudinal design appropriate?

III.  Cross-Sectional 

A.   Age DIFFERENCES (vs. age changes)

B. Problems with this design

C. When is a cross-sectional study appropriate?

IV. Cross-sequential Designs

Discussion questions:

1)   Both longitudinal studies and cross-sectional studies have problems with cohort differences.  How do cohort differences affect the conclusions you draw from your cross-sectional and longitudinal studies, respectively?  What does this have to do with external and internal validity?

2) Think of some potential cohort differences between:

·        20-, 40-, and 60-year-olds

·        3-, 6-, 9-year-olds

3)  What potential confounds are associated with longitudinal and cross-sectional designs respectively?

 V.