Just because a cluster is shown to be statistically signficant does not mean that there exists any shared exposure or etiology which meets the definition of plauibility and causality. As discussed subsequently, this takes considerably more investigation.

Because a particular disease cluster can be due solely to chance, disease clusters can only be hypothesis generating. Therefore additional epidemiologic investigations must be made to look for the same hypothesized etiologic connection in a new population elsewhere in time and space. It can be very difficult to find a similar population to the initial community in which to perform these follow up investigations.

Finally, disease clusters are often highly emotional situations for all the participants, fraught with political, social and scientific pressures.