We have used the method of lattice statics to perform microscopic calculations of the displaced lattice charge far away from an impurity in an alkali metal. The displaced charge is then used to determine with the aid of the continuum approximation the change in solid structure factor and from it to estimate the correction to the residual resistivity due to strain. Our approximate results for this correction are compared with exact lattice static results and it is found that the continuum approximation very often seriously underestimates the effect of strain.