<p>I'm quite sure this question</p>

<p><a href="https://stats.stackexchange.com/questions/320873/a-better-estimator-than-average">A better estimator than average?</a></p>

<p>(whose title is not very appropriate, btw) is a duplicate. I suggested closing it as a duplicate of this one:</p>

<p><a href="https://stats.stackexchange.com/questions/314915/two-measurement-devices-vs-1-device-multiple-measurements">Two measurement devices vs 1 device multiple measurements</a></p>

<p>which seems appropriate to me. However, this isn't the question I had in mind when I thought it was a duplicate. The question I'm looking for should be from this year, about two different measurements (maybe two different instruments) of a same unknown quantity, formulated in terms of random variables (if I remember correctly). I tried using CV search and Google, without success. Can you help me?</p>

<p><strong>EDIT</strong> I recall the question had an answer (or at least a long comment, but I think it was an answer) which said something like "you need to make some assumptions or you can't say anything  about which is the more accurate instrument, because infinite combinations of different errors in the two instruments could give exactly the same measurements. </p>
