&gt; Similarly, the Correlates of War [3] data is every militarized international dispute between 1816-2007 that fits certain criteria—it too is not a sample but the entire population.<p>Its the entire population of wars meeting a certain criteria in that time frame. If that is the topic of interest, then it is also the whole population. OTOH, datasets like that are often used in analysis that is intended to apply to, for instance, &quot;what-if&quot; scenarios about hypothetical wars that <i>could</i> have happened in that time frame, in which case the studied population is clearly <i>not</i> the population of interest, but is taken to be -- while there may be specific reasons to criticize this in specific cases for reasons other than &quot;its the whole population, not a sample&quot; -- a representative sample of a broader population.