private void setDeviation() {
        /*
         **  Compute the proportional deviation from the mean for each
         **  individual parameter value.
         */
        proportional_dev = new double[data.length];
        for (int i = 0; i < proportional_dev.length; i++) {
            proportional_dev[i] = (data[i] + offset) / (mean + offset);
        }
    }