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Computerized quality control, programs for the analytical laboratory (by T.F. Hartley)
I 114
trends in analyticalchemistryry,
vol. 7, no. 3,1988
Attractive alternative to using larger statistical packages Computerized Quality Control, Programs for the analytical laboratory, by T. F. Hartley, Ellis Horwood, 1986, f18.50 (165 pages) ZSBN O85312-964-9
This book offers eleven computer programs written in BASIC, with explanations and discussion, designed to perform some of the tasks currently being carried out in quality control. These programs cover three basic areas of quality control: calibration graphs (linear and non-linear), batch quality control and betweenbatch quality control. These topics constitute the first three chapters of the book. A fourth, small chapter is added with a discussion on laboratory computing. The book is closed with three appendices. The. chapter on calibration discusses three programs: LINCALIB for straight line calibration, and SPLINE and CURVEFIT for nonlinear calibration. Chapter 2 is a good introduction to decision making in batch quality control, that is, the selection of the number of control samples and the conclusions to be drawn from a batch, depending on the number of defective control samples found and/or the level of confidence required. This relationship is given by the ROC-curve (operation characteristic), which can be calculated with the program OCCURVE. The results obtained for control samples by two different methods are usually compared by linear regression. However, because both results contain errors of a similar magnitude, the distance between the points and the regression line have to be measured in a perpendicular direction, which is done in the program GMREG.
In Chapter 3 the cusum V-mask and Trigg methods of detecting a trend in the performance of a method are discussed. First, three utility programs are provided: QCNAME and QCFILER for creating files which can be processed by REPORT, that produces a summary report based on the two aforementioned methods. The optimum parameters of the Vmask necessary to run REPORT can be calculated with VMASKA. GAUSSGEN, SPLINE and a program for the calculation of the ROC curve without outliers are provided in the appendices. Most programs are less than 100 lines long, the longest being about 250 lines, and are available on floppy disk from the publishers. The programs collected in this book constitute a very attractive alternative to using routines from larger statistical packages for microcomputers. First of all because of its modest price (about f 1.80 per program) and secondly because of its good documentation. The discussion of the theoretical background to the methods is limited to what is necessary to understand the software listed in the book and extensive comment is provided on several parts of the programs. A word of caution, however, is appropriate when using ‘private’ software instead of well established packages (BMDP, SISS-PC, etc): namely, one should validate the results obtained very carefully. This point is my greatest concern with this book. On a closer examination of the examples provided for one of the programs, LINCALIB, one finds that an unweighted least-squares method is tested on heteroscedastic data (data with unequal variance). Furthermore the performance char-
acteristics against goodness-of-fit and lack-of-fit are not evaluated by an ANOVA, rather an empiric criterion is applied which is based on the percentage of residual variance calculated from the correlation coefficient. Despite the need to validate any program that is not part of a used and tested package, this book is fully recommended to anyone who is concerned with quality control and who is sufficiently familiar with statistics to evaluate the programs before applying them in practice. The book is also recommended to the novice in the field of quality control, as it contains a very neat treatment of the Bayes rule (without naming it), the V-mask and the Trigg tracking signal. BERNARD G. M. VANDEGINSTE Dr. ir. Bernard G. M. Vandeginste is at the Laboratorium voor Analytische Chemie, Katholieke Universiteit Nijmegen, Toernooiveld, 6525 ED Nijmegen, The Netherlands.
Spectral information Handbook of Znfrared Spectra, by G. Guelachvili and K. Narahari Rao, Academic Press, 1986, US $75.00 (lxx + 851 pages) ZSBN 0-12-3053609
The format of the Handbook is essentially the same as in prior tables of this type, such as the ZUPAC Tables of Wavenumbers for the Calibration of Znfrared Spectrometers by A. R.
H. Cole, which was published by Pergamon Press, and Wavelength Stan-
trends in analyticalchemistryry,
vol. 7, no. 3,1988
Attractive alternative to using larger statistical packages Computerized Quality Control, Programs for the analytical laboratory, by T. F. Hartley, Ellis Horwood, 1986, f18.50 (165 pages) ZSBN O85312-964-9
This book offers eleven computer programs written in BASIC, with explanations and discussion, designed to perform some of the tasks currently being carried out in quality control. These programs cover three basic areas of quality control: calibration graphs (linear and non-linear), batch quality control and betweenbatch quality control. These topics constitute the first three chapters of the book. A fourth, small chapter is added with a discussion on laboratory computing. The book is closed with three appendices. The. chapter on calibration discusses three programs: LINCALIB for straight line calibration, and SPLINE and CURVEFIT for nonlinear calibration. Chapter 2 is a good introduction to decision making in batch quality control, that is, the selection of the number of control samples and the conclusions to be drawn from a batch, depending on the number of defective control samples found and/or the level of confidence required. This relationship is given by the ROC-curve (operation characteristic), which can be calculated with the program OCCURVE. The results obtained for control samples by two different methods are usually compared by linear regression. However, because both results contain errors of a similar magnitude, the distance between the points and the regression line have to be measured in a perpendicular direction, which is done in the program GMREG.
In Chapter 3 the cusum V-mask and Trigg methods of detecting a trend in the performance of a method are discussed. First, three utility programs are provided: QCNAME and QCFILER for creating files which can be processed by REPORT, that produces a summary report based on the two aforementioned methods. The optimum parameters of the Vmask necessary to run REPORT can be calculated with VMASKA. GAUSSGEN, SPLINE and a program for the calculation of the ROC curve without outliers are provided in the appendices. Most programs are less than 100 lines long, the longest being about 250 lines, and are available on floppy disk from the publishers. The programs collected in this book constitute a very attractive alternative to using routines from larger statistical packages for microcomputers. First of all because of its modest price (about f 1.80 per program) and secondly because of its good documentation. The discussion of the theoretical background to the methods is limited to what is necessary to understand the software listed in the book and extensive comment is provided on several parts of the programs. A word of caution, however, is appropriate when using ‘private’ software instead of well established packages (BMDP, SISS-PC, etc): namely, one should validate the results obtained very carefully. This point is my greatest concern with this book. On a closer examination of the examples provided for one of the programs, LINCALIB, one finds that an unweighted least-squares method is tested on heteroscedastic data (data with unequal variance). Furthermore the performance char-
acteristics against goodness-of-fit and lack-of-fit are not evaluated by an ANOVA, rather an empiric criterion is applied which is based on the percentage of residual variance calculated from the correlation coefficient. Despite the need to validate any program that is not part of a used and tested package, this book is fully recommended to anyone who is concerned with quality control and who is sufficiently familiar with statistics to evaluate the programs before applying them in practice. The book is also recommended to the novice in the field of quality control, as it contains a very neat treatment of the Bayes rule (without naming it), the V-mask and the Trigg tracking signal. BERNARD G. M. VANDEGINSTE Dr. ir. Bernard G. M. Vandeginste is at the Laboratorium voor Analytische Chemie, Katholieke Universiteit Nijmegen, Toernooiveld, 6525 ED Nijmegen, The Netherlands.
Spectral information Handbook of Znfrared Spectra, by G. Guelachvili and K. Narahari Rao, Academic Press, 1986, US $75.00 (lxx + 851 pages) ZSBN 0-12-3053609
The format of the Handbook is essentially the same as in prior tables of this type, such as the ZUPAC Tables of Wavenumbers for the Calibration of Znfrared Spectrometers by A. R.
H. Cole, which was published by Pergamon Press, and Wavelength Stan-