The researchers began with five candidate trees for Indo-European, lettered A-E, one generated from the phylogenetic software, two modifications of it and two suggested by Craig Melchert, a historical linguist and Indo-Europeanist. The trees differed mainly in the placement of the most ambiguous group, the Germanic languages, and Albanian, which did not have enough distinctive characters to place it exactly. Tree A contained 14 incompatible characters; B, 19; C, 17; D, 21; E,18. Trees A and C had the best compatibility scores. The incompatibilities were all lexical, and A's were a subset of C's.