Confusion in terms in "Long" and "Wide Format" for longitudinal and intensive longitudinal studies.

The terms wide and long format datasets are used slightly differently in intensive longitudinal (IL) and longitudinal studies (see 1, 2, 3). Although IL and longitudinal studies are related, they differ in their purpose, and thus data processing. In this article, we’ll explain the difference in terminology. 

In IL studies (LifeData datasets), each row is an individual prompt in long format, while in wide format each row is a participant’s session. 

Although there may be differences in the terminology used in IL and longitudinal studies, these differences become clear when you look at how data is organized in each type of study. 





Intensive longitudinal

Each session has a row

Each prompt has a row


Each ID has a row

Each session has a row


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