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The Adoption of Agricultural Technology - Food Security Group

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opposite strategy <strong>of</strong> throwing as many independent variables as possibleinto the equation is not advisable either. <strong>The</strong> use <strong>of</strong> such techniques will beefficient only if we have a clear understanding <strong>of</strong> the data with which weare working.CoeffIcIentProIMIbIIftyConstantTENMONAGE-1.3670.8931.868-0.0120.4810.3530.2660.009-2.8422.5317.016-1.4450.0050.0110.0000.148Sample sizeLog <strong>of</strong> likelihood function318-192.7Chi-square statistic for significance <strong>of</strong> equation 71.4Degrees <strong>of</strong> freedom for chi-square statistic 3Significance level for chi-square statistic 0.000Cases correctly predicted 72.4%One way <strong>of</strong> presenting information from probit or logit regressions is toshow how changing one independent variable alters the probability that agiven individual is an adopter. In ordinary least squares regression, acoefficient can be interpreted directly as the change in the vi.llue <strong>of</strong> thedependent variable associated with a change in one unit <strong>of</strong> the independentvariable associated with that coefficient. This is not true in probit or logitregressions; the change in probability <strong>of</strong> adoption given a change in one <strong>of</strong>the independent variables depends not only on the coefficient <strong>of</strong> thatvariable but also on the levels <strong>of</strong> all the other independent variables.As an example, the estimated probability <strong>of</strong> adoption in a logit model isgiven by:probability <strong>of</strong> adoption = F(b'x),where:F(b'x)1 + e-b'xis the cumulative logistic probability distribution. <strong>The</strong> expression b'x isdefined as:78

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