Longitudinal Data

Gist

There's a lot of heterogeneity among individuals but if we do a repeated measure of an individual- there is a high chance that the observations are correlated. Individuals may respond more to interventions than the population.

Missing data

An important aspect of longitudinal data because the individuals who drop out and those who stay till the end of the study:

If subjects drop out because they already have derived full benefit from an effective treatment, an analysis that only considers those subjects who completed the trial may fail to show that the treatment was beneficial relative to the control condition

References

1. Gibbons RD, Hedeker D, DuToit S. Advances in analysis of longitudinal data. Annu Rev Clin Psychol. 2010;6:79-107. doi: 10.1146/annurev.clinpsy.032408.153550. PMID: 20192796; PMCID: PMC2971698.