"Failing the possibility of measuring that which you desire, the lust for measurement may, for example, merely result in your measuring something else - and perhaps forgetting the difference - or in your ignoring some things because they cannot be measured." A quote by British statistician George Udny Yule that can be used in discussing the validity of measurements. The quote is contained on the last page of his famous 1921 British Journal of Psychology paper "The essentials of mental measurement."
The quote is commonly paraphrased as "In our lust for measurement, we frequently measure that which we can rather than that which we wish to measure... and forget that there is a difference."