Time series analysis (TSA) is one of a number of new methods of data a
nalysis appropriate for longitudinal data. Simonton (1998) applied TSA
to an analysis of the causal relationship between two types of stress
and both the physical and mental health of George m. This innovative
application demonstrates both the strengths and weaknesses of time ser
ies analysis. Time series is applicable to a unique class of problems,
can use information about temporal ordering to make statements about
causation, and focuses on patterns of change over time, all strengths
of the Simonton study. Time series analysis also suffers from a number
of weaknesses, including problems with generalization from a single s
tudy, difficulty in obtaining appropriate measures, and problems with
accurately identifying the correct model to represent the data. While
careful attempts are made to minimize these problems, each is present
in the Simonton study, although sometimes in a subtle manner. Changes
in how the data could be gathered are suggested that might help to sol
ve some of these problems in future studies. Finally, the advantages a
nd disadvantages of employing alternative methods for analyzing multiv
ariate time series data, including dynamic factor analysis, are discus
sed.