Review : Cross - Validation and the Free - RDr
نویسنده
چکیده
Macromolecular crystallography is an example of a scientiic measurement problem which starts with a diiraction pattern and ends with an atomic model. The path in between is suuciently complex that it is hard to relate the precision of the nal model to the original measurements. As a result it is hard to distinguish between an improvement to the model which ts a genuine feature of the signal, and one which merely ts noise in the data. A statistical technique, Cross Validation, is available to counter this problem. Its crystallographic application has been pioneered by Axel Br unger in the form of the Free-R factor (Br unger, 1992).
منابع مشابه
Finding Conceptual Models to Assist Validation
Many approaches to knowledge based systems (KBS) development attempt to build complete systems that are mostly considered final before they are put into production. Verification and Validation (V&V) is seen as an activity performed before the system is installed and little consideration is given to incremental KA, maintenance or validation of the system after installation. We take a situated vi...
متن کاملRipple Down Rules: A Technique for Acquiring Knowledge
Knowledge is becoming increasingly recognized as a valuable resource. Given its importance it is surprising that expert systems technology has not become a more common means of utilizing knowledge. In this chapter we review some of the history of expert systems, the shortcomings of first generation expert systems, current approaches and future decisions. In particular we consider a knowledge ac...
متن کاملDisturbance rejection performance analyses of closed loop control systems by reference to disturbance ratio.
This study investigates disturbance rejection capacity of closed loop control systems by means of reference to disturbance ratio (RDR). The RDR analysis calculates the ratio of reference signal energy to disturbance signal energy at the system output and provides a quantitative evaluation of disturbance rejection performance of control systems on the bases of communication channel limitations. ...
متن کاملDetermining optimal value of the shape parameter $c$ in RBF for unequal distances topographical points by Cross-Validation algorithm
Several radial basis function based methods contain a free shape parameter which has a crucial role in the accuracy of the methods. Performance evaluation of this parameter in different functions with various data has always been a topic of study. In the present paper, we consider studying the methods which determine an optimal value for the shape parameter in interpolations of radial basis ...
متن کاملResonant diffraction radiation from an ultrarelativistic particle moving close to a tilted grating.
A simple model for calculating the diffraction radiation characteristics from an ultrarelativistic charged particle moving close to a tilted ideally conducting strip is developed. Resonant diffraction radiation (RDR) is treated as a superposition of the radiation fields for periodically spaced strips. The RDR characteristics have been calculated as a function of the number of grating elements, ...
متن کامل