This series of books aspires to be a practical reference guide to a range of numerical techniques and models that an estimator might wish to consider in analysing historical data in order to forecast the future. Many of the examples and techniques discussed relate to cost estimating in some way, as the term estimator is frequently used synonymously to mean cost estimator. However, many of these numerical or quantitative techniques can be applied in other areas other than cost where estimating is required, such as scheduling, or in determining a forecast of physical characteristic, such as weight, length or some other technical parameter.