  In usual demographic analysis, force of mortality is a function of one
variable, that is, of age. In this article bi-variate and multivariate force of
mortality functions are introduced for the first time to explain mortality
differentials. The pattern of mortality in a population is one of the strong
influencing factors in determining the life expectancies at various ages in the
population. Considering univariate functions of age only to understand the
human mortality data without associating with other variables could lead to
incomplete analysis. The reasons behind declining forces of mortality globally
could be studied using the proposed functions. Other applications of
multivariate forces of mortality could be in actuarial sciences.
