diagnostic technique

NOUN
20 LETTERS · STARTS WITH D

diagnostic technique is a valid 20-letter word worth 37 points in Scrabble and 42 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2I1A1G2N1O1S1T1I1C3T1E1C3H4N1I1Q10U1E1
2 + 1 + 1 + 2 + 1 + 1 + 1 + 1 + 1 + 3 + 0 + 1 + 1 + 3 + 4 + 1 + 1 + 10 + 1 + 1 =37 PTS
DOUBLE WORD → 74TRIPLE WORD → 111
MEANING

What does diagnostic technique mean?