Accuracy And Uncertainty... They Are Not The Same

How tall are you?  In everyday conversation you probably would answer in a general way by saying, “I’m five foot, eight inches tall.”  But how true is your answer?  Are you exactly 5’8” tall?  It’s likely you rounded up your height to the nearest inch, so in reality our height is probably somewhere between 5’7”and 5’8”. If we want a specific and more reliable answer, we must look a little closer.

Think for a moment about measuring someone’s height.  Is the measuring tape or ruler precisely inscribed and is it printed on a stable medium?  When you measured the height did the person have shoes or socks on? Did you include the hair on top of their head? Even if you placed a perfectly horizontal rod on the top of their head, there likely was hair in between. Did you make more than one measurement to double-check? If you measured multiple times and averaged them together, did you use the same measuring device each time? As you can surmise, there is always a margin of doubt about any measurement.