If you want to check accuracy, do an Ice Point Melt Test.
Fill a glass full of ice, pour in some water to the top, let the ice melt a bit, stick the thermocouple, or whatever in there, swirl it around a bit and that should give you your offset from 32°F, or 0°C.
I have a bunch of NIST Certified stuff here, but people don't understand what this really is
All this is, is NIST is telling you how screwed up your stuff is and the offsets you need to deal with.
