Application of Forward and Backward Methods to Determine Factors Effecting Life Expectation in South Tapanuli District

Life expectancy is an indicator used to assess health status. To increase life ex pectancy, of course, cannot be separated from various factors. To find out what factors signif icantly affect life expectancy, the authors use forward and backward methods . The purpose of this method is to reduce one by one the estimating variables that do not have a significant effect on the response variable until the desired estimator equation is obtained. The estimator equation obtained is ˆ Y = 64,186+0,020X1−0,129X2+0,036X5, where X1is the percentage of households with the widest non-soil/timber floor, X2 is the percentage of the population having health complaints during the past month and X5 is the percentage of households with the widest wall being a wall. The magnitude of the variance explained by the estimator was 98.28%, so it can be concluded that the estimator model obtained is good enough to be used as an estimator of life expectancy in South Tapanuli Regency.