MeanThe average of a set of values (figures) calculated by summing them and then dividing the sum by the number of values. For example, the mean of the seven values 7, 4, 6, 7, 5, 7 and 6 is 42 ÷ 7 = 6. If the figures are ranked in order (namely, 4, 5, 6, 6, 7, 7, 7) the middle value in the order, in this case 6, is called the 'median'. The figure one quarter and three quarters of the way along the rank are called the 'lower quartile' and 'upper quartile' (in this case 5 and 7) respectively. the value which occurs most often (7 in this example) is called the 'mode'. These terms are much used in the statistical analysis of quantitative data on birds.
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From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver