In statistics, the theoretical curve that shows how often an experiment will produce a particular result. The curve is symmetrical and bell shaped, showing that trials will usually give a result near the average, but will occasionally deviate by large amounts. The width of the “bell” indicates how much confidence one can have in the result of an experiment — the narrower the bell, the higher the confidence. This curve is also called the Gaussian curve, after the nineteenth-century German mathematician Karl Friedrich Gauss. (See statistical significance.)
Note: The normal distribution curve is often used in connection with tests in schools. Test designers often find that their results match a normal distribution curve, in which a large number of test takers do moderately well (the middle of the bell); some do worse than average, and some do better (the sloping sides of the bell); and a very small number get very high or very low scores (the rim of the bell).