The lognormal distribution

Abstract

As already mentioned in sections 4.3, 5.1, 9.1 and 12.7, the normal distribution is not always completely suitable in biology because many biological variates cannot take negative numerical values and have positively skewed frequency distributions (sections 13.2 and 13.7). The lognormal distribution is often better adapted to biological data. While the normal distribution extends theoretically from - ∞ to + ∞ and covers negative values (Figure 14.1.1, top and bottom), the lognormal distribution extends from 0 to + ∞ and is limited to positive values (figure Figure 14.1.1, center).