|First described by||Karl Pearson| |Purpose||To roughly assess
the probability distribution of a given variable by depicting
the frequencies of observations occurring in certain ranges of
values| In statistics, a histogram is a graphical representation
of the distribution of data. It is an estimate of the
probability distribution of a continuous variable and was first
introduced by Karl Pearson. A histogram is a representation of
tabulated frequencies, shown as adjacent rectangles, erected
over discrete intervals (bins), with an area equal to the
frequency of the observations in the interval. The height of a
rectangle is also equal to the frequency density of the
interval, i.e., the frequency divided by the width of the
interval. The total area of the histogram is equal to the number
of data. A histogram may also be normalized displaying relative
frequencies. It then shows the proportion of cases that fall
into each of several categories, with the total area equaling 1.
The categories are usually specified as