Larrv Potteri and ~ r u c Brown e Portland State University Portland Oregon 97207
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A Program to Evaluate Quantitative Analysis Unknowns
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Since the advent of computers, manv programs have been reported that were designt:d tograde &uanritativeanalflical lahoratorv results (1-31 These programs arc. similar in that purpose is the routine-grading of analytical retheir sults, using a grading scheme devised locally. We report here a batch-oriented program, QGP7, written in Fortran IV that will not only perform routine grading using several grading algorithrns,h& will also calculate \,ariola st&tical measures by which tbp class perfurmance can be evaluated and cnmul&e. data collected. ~ ~ ~ The program will confirm the student's calculations from the analvtical data su~nliedon a header card and the student's data cards. Unlike grading programs written to confirm calculations for specific analytical procedures (4-71, the calculation coding in QGP7 is written in general terms. The present 14 calculation types can be easily expanded, and range from very non-specific (e.g.: acid-base titrations or gravimetric analyses) to unique (e.g.: the stoichiometry of the zinc ferrocyanide precipitation titration). Each calculation type has several options for various methods of sample dispensing. Calculation errors are identified on the output listing. Where quadruple samples are analyzed, the program will apply the Q-test (8); any datum that fails the Q-test is rejected from further calculations and is identified on the output listing. The student's mean value is calculated from the non-rejected samples, and the relative standard deviation (coefficient of variance expressed in parts per thousand) is calculated. The presence of random errors are detected and these data
lation or other data errors, for significant place errors, or for late reports. In addition, o~tionall,onuspoints can he awarded for student's quadruple data that are borh accurate and precise. The program calculates various summary statistics and optionally prepares lists in alphabetic and grade order. Tn evaluation calculated . . .the .--. .~ ~ mode. - , statistical ~ ~data are ~ ~ ODtionallv after the grading mode, or these statistical data may be obtained directly from long term accumulations of students' data cards for the unknowns. The average and standard deviations. -. ~-~~~~~ the relative deviation. and the relative standard deviation are calculated from thekeighted average (12) and from the ~ o o l e dvariance (1 . 3): .. if a normalizing value is supplied, these statistics are also calculated for tKe normalized students' data. Lastlv. -.the summations required for the Z-test (14) will he listed for the normalized data; an auxiliary program can be used to calculate the Z-statistics for the unknowns. The program has been fully documented and checked out on an 8K IBM 1130 (14 overlays), a Honeywell H-66/40, a CDC Cyber-73 (4 overlays) and a Harris H-220. A copy of the documentation is available on request. There is a nominal charge to cover computer center and mailing expenses for a copy of the Fortran IV program on magnetic tape or as the source deck of -4000 cards. One of the authors, BWB, would like to thank the University Computer Center for support during the evolution of this program.
values. The absolute and relative average and standard deviations are calculated for each of these sample means. In the grading mode, the grading procedure is selected by either with the the user, ~h~ student2s data mav be
Oregon. June li,1965. (3) Jonea, D. E., and Lytle, F.E., J. CHEM. EDUC., 50,285 11973). IO w a r t o ~ ~ , ~ . ~ . , s n d ~ uJ.rA,, ~ bJ.CHEM. ut, EDUC.,~S,~O~IIYW (51 neutsch.J.L.,andZdoznak,H.N., J.CHEMEDUC.,53,30sl1976). (61 Hamilton, J. C.. H3ler.F. W.,Thomas,E. D., endThomas S. S.,J. CHEMEDUC., 53,
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Literature Clted
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Or the viation of the unknown as calculated standard deviation for the analytical procedure, each of which may be applied either to the calculated mean or to the true assay. Subsequent grading increments, up to a maximum of ten, may follow either an arithmetic or geometric (12) progression, Four different grades are derived from these data, and additional grading algorithms can be added to the program. Optional penalties can he applied for failure to apply the Q-test or erroneous application of the Q-test, for calcu-
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p p 16.21. (11, Blsedal. W . J., Jefferson, J. H.. and Knight. H. T.,J. CHEM EDUC., 2% 480 (1952). nureau (121 KU, H. H I E ~ ~ ~ O ., ) , . ~ ~ M ~ ~D i ~~ i Calibration: ~~ ~ ~ ~ National ~ ~ DOF ~ , I, U.S.~overnmentprinting office. standards special publiestion 3 ~ 4volume Wsshington,D.C.,1 9 6 9 . ~312414. ~. (IS) Msndel. J., 'The Statlatical Analysis of Ezprimental Dsfa,"Interscience, New York. 1964, pp 65-68. (141 Stee1.R. G.D..andTomie.J.H.."Principle6~nd Promdu~~ofStatistics~McGrawHill. New York, 196O.p~.3640.
'Present address: Computer Department, Portland General Electric Company, Portland, Oregon 97205.
Volume 55. Number 7,July 1978 1 441
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