What is SHAZAM Quad Precision?

Quad Precision is a higher precision mode of SHAZAM. Most analytical software packages (including SHAZAM) typically perform calculations in double precision but report the answer in less precision so that any accumulated rounding error is simply truncated in the reported results.

However, SHAZAM is also capable of Quadruple precision floating-point calculations where floating point numbers occupy 16bytes instead of the usual 8bytes used for double precision floating point calculations. This capability of SHAZAM is unique among the class of econometrics, statistics and analytics software that SHAZAM is part of.

Higher precision is useful when there are a lot of calculations being performed (such that rounding error accumulates to a large degree) or where source data is highly precise to begin with.

Note that Precision is different from Accuracy and measurements are usually considered valid when they are both Accurate and Precise. In optimization algorithms it is possible for higher precision internal calculations to lead to more accurate final results because tolerances are smaller.

Quadratic Precision mode is mentioned on pages 474, 475 and 477 of the SHAZAM version 10 Reference Manual.