Have you ever checked the digital ones? The best digital one I have is out +8% and -1.3º F The analogue hygrometers out of the box were spot on (+/- 0.11% is the best the salt test can manage) and they can be corrected when wrong. The cheap digital thermometer typically are resistive style ones and the best the specs can support is +/- 2ºF My accurite is 1.7 high and 11% high. Good digital thermometers are generally too expensive for most people to buy I use one from my work. Cheap LC ones are generally good but not great of in the enclosure reading they can be used to figure out how good or bad the cheapo digital ones are... I am a self admitted spaz about it I do a lot of calibration of instruments professionally. I can't sleep knowing temps could be more than 1ºF +/- and humidity more than 5%+/- . Some are not as fussy as I am.