Keep in mind that there are almost endless variables internal and external that can factor in and limit one's ability to approach a perfect sensor and it's perfect measurement. Things like sensor self-heating effects caused by the electrical interface between the sensor and the circuit required to bias or excite the sensor. My signature below is a reminder that it's known in science that it's hard to prove one can measure something specific without the measurement method being used having an influence on the measurement being taken. Not unlike asking a subject person to smile as you take a picture of the person, the pictured smile is seldom an accurate representation of the smile you see from that same person when he/she doesn't know they are being watched or photographed.
Accuracy is truly a complicated subject when you try to consider, define, or compensate for all the possible causes of deviation from 'true accuracy'. And never take page one datasheet accuracy specifications at face value. The marketing guys write page one, the real engineers are tasked with trying to tell the truth about those claimed specifications using small print and nearly impossible assumptions and external conditions one has to use to meet those page one 'highlight' specs.
Lefty