<p>There have been several questions on the site that more or less ask about clustering longitudinal data.</p>

<ul>
<li><a href="https://stats.stackexchange.com/questions/3331/is-it-possible-to-do-time-series-clustering-based-on-curve-shape">Is it possible to do time-series clustering based on curve shape?</a></li>
<li><a href="https://stats.stackexchange.com/questions/3238/time-series-clustering-in-r">Time series 'clustering' in R</a></li>
<li><a href="https://stats.stackexchange.com/questions/2777/modelling-longitudinal-data-where-the-effect-of-time-varies-in-functional-form-be">Modelling longitudinal data where the effect of time varies in functional form between individuals</a></li>
<li><a href="https://stats.stackexchange.com/questions/13442/how-to-find-groupings-trajectories-among-longitudinal-data">How to find groupings (trajectories) among longitudinal data?</a> (This is the most recent question)</li>
</ul>

<p>This one may be another that could be quite large in scope (similar to the now series on R GUI's). Perhaps to reduce the workload we could get volunteers to write a brief abstract about different routines people have developed and applied examples. </p>

<p>Panel data that these techniques are applied to tend to be really complicated, and so it seems to me these clustering techniques can be really helpful for exploratory data analysis. The techniques being more complicated make it more difficult to make a blog post accessible to a wide audience, but I suspect the number of people working with similar panel data would make the post of interest to a large number of the members of this site.</p>
