A description is given of the method of determining the gradient m and intercept c of a straight line when one variable is error-free, while the other is subject to error. Based on this theory, a computer program was written to compute the parameters of the line, i.e.mandc, with their standard errors, andx cai for those cases where the errors of the input data are known. Data obtained from nuclear physics experiments (where data have non-constant errors) ivere used to test this method, which was found useful in determining the parameters of the best straight line, and their standard errors. The usefulness of this method for non-nuclear physics undergraduate experiments (or for data with constant errors) is also discussed.