Pagel et al. used hypothesized reconstructions of proto-words from seven language families listed in the Languages of the World Etymological Database (LWED). They limited their search to the 200 most common words as described by the Swadesh fundamental vocabulary list. Twelve words were excluded because proto-words had been proposed for two or fewer language families. The remaining 188 words yielded 3804 different reconstructions (sometimes with multiple constructions for a given family). In contrast to traditional comparative linguistics, the researchers did not attempt to "prove" any given pairing as cognates (based on similar sounds), but rather treated each pairing as a binary random variable subject to error. The set of possible cognate pairings was then analyzed as a whole for predictable regularities.