Abstract: A method of computer generating a subsurface characteristic model which is substantially consistent with readings taken in a well with a well logging device. A set of actual measurement values which represent readings taken over a given depth interval of a well is derived. An initial trial model of the subsurface characteristic under investigation is then selected. Next, a simulated measurement value at a particular depth level is generated by applying the approximate response characteristic of the logging device to the model. The simulated measurement value at the particular depth level is compared to the actual measurement value at that depth level and an error value is generated as a function of the comparison. The model is then modified in accordance with the error value, the modification being performed over a depth interval which includes the model beds within a preselected span from the particular depth level.