Many academics specializing in historical linguistics via the comparative method are skeptical of the conclusions of the paper, and critical of its assumptions and methodology. Writing on University of Pennsylvania blog "Language Log", Sarah Thomason questions the accuracy of the LWED data on which the paper was based. She notes that LWED lists multiple possible proto-word reconstructions for most words, increasing the possibility of chance matches. Pagel "et al.". anticipated this criticism and state that since infrequently used words generally have more proposed reconstructions, such errors should "produce a bias in the opposite direction" of what the statistics actual shows (i.e. that infrequently used words should have larger cognate groups if chance alone was the source). Thomason also argues that since the LWED is contributed to primarily by believers in Nostratic, a proposed superfamily even broader than Eurasiatic, the data is likely to be biased towards proto-words that can be judged cognate. Pagel "et al.". admit they "cannot rule out this bias" but say they think it is unlikely bias has systematically impacted their results. They argue certain word types generally believed to be long lived (e.g. numbers) do not appear on their 23 word list, while other words of relatively low importance in modern society, but important to ancient people do appear on the list (e.g. "bark" and "ashes"), thus casting doubt on bias being the cause of the apparent cognates. Thomason says she is "unqualified" to comment on the statistics themselves, but says any model that uses bad data as input cannot provide reliable results.