Yes, DISTRIBUTION is a Scrabble word!

Letter values in Scrabble US: D 2, I 1, S 1, T 1, R 1, I 1, B 3, U 1, T 1, I 1, O 1, N 1.

Is it a valid word?

DISTRIBUTION is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(statistics) an arrangement of values of a variable showing their observed or theoretical frequency of occurrence
the spatial or geographic property of being scattered about over a range, area, or volume
the act of distributing or spreading or apportioning
the commercial activity of transporting and selling goods from a producer to a consumer

Also: statistical distribution.