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Comment by Mezzie | Hacker News Reader

Precision and accuracy are slightly different mathematical concepts, as demonstrated by this image [0]:

[0]: https://wp.stolaf.edu/it/files/2017/06/precsionvsaccuracy_cr...

To be honest accuracy Vs precision has always kind of makes sense to be but also not.

If something is extremely accurate, it will also be extremely precise by necessity, it seems like? The difference between low precision but high & low accuracies is that points are closer to center. If you keep getting closer to center, more accurate, don't you necessarily get more precise too?

Precise has always felt like a shitty alternate of accuracy. It's accuracy but with drift, accuracy to not the right place. But if you're accurate, you're both.

Am I missing something? And, here specifically, if this is a case of very high precision but lower accuracy, can someone explain what the drift from center is about? Isn't a radius a radius? Where is the drift off center in these measures?

I wrote about precision here if you are interested. You first need precision before you can start even talking about accuracy (otherwise there is no "center").

https://alexpetralia.com/2023/01/31/what-does-it-mean-for-da...

Something is accurate in this sense if the "true" value (ignoring any philosophical implications thereof) is contained in the error bounds of the measurement. What you're noting is that a high accuracy measurement will, upon application of statistics, allow you to derive a new measure which is both high-accuracy and high-precision, regardless of the low precision of any inputs. Not all things being described with accuracy and precision are the result of processing large amounts of data though.

I don't like the lower left quadrant of that diagram, because it's not clear that it's not centered on the target. It would have been more clear if the cluster was smaller so it could be moved to not be centered on the target.

Accurate but imprecise means we can throw more and more shells down range and eventually hit the target. Inaccurate and imprecise means we may never hit the target. Inaccurate but precise also means we may never hit the target, but if we could introduce a second, different measurement that was accurate, we could compensate.

I saw a Greek food stall in town a couple of years back with the statement "Food delivered with mathematical accuracy" which just bugged the hell out of me lol.

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