Thermometers?

Question

Apart from different thermometer's being made of different substances what are some other reasons why they don't give accurate measurements of temperature?

Answer 1

There's always a tradeoff between making them cheap and making them accurate. You can take almost any thermometer and carefully calibrate it against known references to get accurate measurements. It's much easier to make an accurate thermometer than to make an accurate hygrometer, to measure relative humidity.

Answer 2

Mass manufacturing variances and consumer placement.