The term 'accuracy' and 'precision' are bandied around a bit, particularly when discussing sensors. There doesn't seem to be a consistent usage. I tried to comment on this a a recent post, but was unsuccessful in submitting something. Are there accepted definitions within Public Lab?
I don't think there is any debate about what those words mean, but I find it hard to use them correctly all the time. The only sensors I have used with data loggers are very cheap and probably not very accurate or precise. A $1.00 temperature sensor is not designed to report a temperature that is closer than about one or two degrees from the actual temperature, but that is good enough accuracy for everything I have used them for. I am much more impressed by DIY data loggers because of their potential to be incredibly inexpensive and adaptable than by their potential to be highly accurate. For my projects I can work around poor accuracy, but if the parts are expensive I would have to get a job.
Concern about the precision of sensors is probably related to the problem of drift--whether the accuracy of the sensor changes through time. A lot of these little electronic sensors seem to drift as temperature changes. That might be okay for your project, but it's important to be aware of it.
I was really impressed that the MMA8451 accelerometer could measure the length of a bayonet on two different days to within about 7 mm with no apparent difference in accuracy between the two days. But acceptable accuracy depends strongly on the goals of the project. I guess there is no universal guideline for either accuracy or precision.
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