How Accurate is Accurate?

[Brazen17]

I have five digital temp/hygrometers and 1 analog style hygrometer. Except for the analog they are from the same manufacturer with 3 of them being the same model. Of the 3 same models they are all reading 73F. Of the other 2 one is also reading 73F and the other 74.7F. This seems close enough and reasonably accurate. The problem is in the humidity readings. Two of the three identical models reaad 21% RH (though they temporarily drop to 16%) and the third reads 31%! The other 2 digital models are reading 21% and 24% which seems in line. The analog is reading ~24% but it takes quite a bit longer to adjust. I am thinking about taking the one reading 31% back aand replacing it.

Any thoughts on how accurate we need to be here? I think 3-5% is not a big deal but 10% seems kind of high. The analog will be used in my son's tarantula enclosure, one of the digitals will go in my daughters Argentine Tegu's cage and the rest will go in various snake viv's. The one going into the GTP's viv has an indoor and outdoor temp reading which I though would be good to get the temp readings at two different vertical locations. Cheers :)

[vendettaseve]

The one thats reading 10% over probly has faulty parts in it, or was not calibrated correctly when it was made. Ambient Humidity is difficult to glean super accuratly without really expensive equipment.

Id say, yes replace the one thats giving you crazy numbers, and provided things seem to be about right and your animals are comfortable, its not a huge worry.

[stephanbakir]

5% can make a difference, especially with sensitive snakes like GTPs and burms.

[Lankyrob]

in terms of temp i would want no more that 1f difference - humidity i wouldbe happy with a difference of 5% on the readings.

[stephanbakir]

It depends what its for though but yeh, you want them to be accurate as possible especially if you ever plan to use the thermometer/hygrometer in an incubator

[mykee]

Cheapo thermometers are accurate to within +/- 3 degrees.
You want accuracy to within 1/10 of a degree? Shell out the big bucks and buy Herpstat.

[Brazen17]

Cheapo thermometers are accurate to within +/- 3 degrees.
You want accuracy to within 1/10 of a degree? Shell out the big bucks and buy Herpstat.

Don't need nothing that fancy! Temps seem to be in line but it's the humidity I am more worried about. Just want to make sure the critters are in their proper ranges. I don't have any plans to breed at this time...yet.

[Lankyrob]

Humidity should cycle diring the day anyways, we spray early morning and then let the vivs "dry out" to 50% over 24 hours before respraying. Our gtp gets an afternoon/evening spray as well as his arboreal viv dries out quicker having more vertical space and less floorspace.

[Web Wheeler]

Cheapo thermometers are accurate to within +/- 3 degrees.
You want accuracy to within 1/10 of a degree? Shell out the big bucks and buy Herpstat.

Herpstats are no where near an accuracy of 1/10 of a degree; more like 9/10 degrees (see here (http://www.spyderrobotics.com/products/herpstat_nd.html)).

I happen to be doing some testing on my Herpstat ND for use in an incubator used for hatching Green Tree Python Eggs. See here for the the real-time results. (http://aqua-terra-vita.net/etcPoller/) Please note: large fluctuations in temps indicate I have opened the incubator door and that my incubation will end around June 1st, 2011.