Errors in Experimental Results

Whenever one measures anything, there is an error associated with the measurement. If you try to measure the distance between two points with a ruler, you might find that it is 5". On your ruler, inches are subdivided down to 1/16" markings. If you look carefully, you might see that the distance is actually between 4 31/32" and 5  1/32" (half a tic-mark up or down).

The range of values around the measured value is the error in the measurement - in this case, from 4  31/32" to 5 1/32". The result is written as 5 ± 1/32, implying that the correct result is anywhere in the range of 5 - 1/32 ( = 4 31/32) to 5 + 1/32 ( = 5 1/32).   ±1/32" is "the error" in the measurement.