Historical Linguistics and Language Families 10, Exercise 1: Finnish and Hungarian

Correspondence: Finnish -s- against Hungarian -z in vesi / víz and käsi / kéz.
The same pair of sounds appears in both words. (This is my reading of the
table; the source gives the words, not the set.)

Why three words are not enough: a regular correspondence needs enough
examples to rule out chance and to test for conditioning. Three items is a
very small sample, so the data are consistent with a relationship but do not
prove one.

Further evidence the source lists (Wikipedia, Uralic languages): shared
traits such as agglutination, extensive case systems (Finnish has 15) and
vowel harmony in many languages; the early etymologies (Rudbeck 1717, about 40
of about 100 still valid); and Sajnovics's 1770 argument from grammatical
features.