Graphical Analysis DavidR. Dice. Digipac Computer Consuh ing, Prince Albert Saskatchewan, Cana da S6V 083 Hardware: Apple 11, 48 K, optional printer Software: Applesoft Components: One disk and manual Level and Subject: General chemistry -high school and coliegl Cost: $23.95
tively, the data, presumably from an experiment carried out by the student, may be entered directly during the interaction and stored permanently, if desired, a t that time. The program is designed with a good deal of built-in flexibility. At the most basic level, i t may serve to teach the fundamentals of graph-drawing. The manual provides advice and information on the correct method of graphical presentation of data and the proeram allows the student to oractice the cnowledee mined from it. The btudent mav ~~-~~ chwse the position of the origin, the maximum value for each variable along the axes, and the subdivision and labelling of the axes. The prucram then plot%the experimental points un the grid iprrifird and prrcrnts fwu wtions fur their "connertiun." Onr of these idthe "dot-to-dot" method soecificallv condpmned in the manual.'l'hr other ~lltiun~ , n line rpprrscntiug a lrast squarr* analyzie of t h data. ~ This uption otlrrs a chuire ammy five alternatives in sequence from a linear plot (y = a bx) to a fifth order plot (y = o bx ex2 dx3 ex4 f x 5 ) . The program offers no advice concerning how this choice is to be made. Using anequation of the form selected, the program plots the curve, extrapolated if desired, that hest fits the experimental data. I t then provides values for the constants (a, b, etc.) in the equation of this curve, and also values for the error of estimate and correlation coefficient which describe how well the curve fits the data. Within this framework, the program allows manipulation of raw data so that various functions of these can be calculated and plotted. The functions available include reciprocals, logarithms (both base-10 and natural), exponents, combination with a constant, and trigonometric functions. (On the disk that I have, these trigonometric functions do not ooerate.) The mathematical mmipulaf~anaare a11 d m e infrrnally and t h ~ rcaults can he d~iplayrdun the scrwn so that axes may he chosen properly. Using this facility, the student may search among the manipulated variable values, through plotting and application of the least squares analysis, for linear relationships. With all these ootians a t hand. the ore~~
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This package presents an effective proh lem-solving approach to the subject of ex perimental data analysis. The graphic ant dynamic aspects of the screen display makt this a far more effective tool than a texthool and more than a match for instructors usin! static devices such as blackboards and over head or slide projectors. Using this program a student can experiment with a variety o formats, searching for the most instructiw visualization of the relationship hetwee~ variables. The program allows a consideration of dab from either of two general sources. The dat; may be provided on the disk as a part of thq program, stored there by the instructor anr available when the student loads the pro gram. The program is supplied, in this way with a sample set of data for study. Alterna
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dial facility for some and as am enrichment for others, depending on the options exercised. As well, i t seems to me that it would provide excellent class presentations of data and their analysis especially if the output is projected on a large screen. In student use, the presence of all these options might prove disconcerting or confusing. Although the manual stresses the search for linear relationships, the availability of the high-order least squares analysis is tempting. Students should be aware of the general shapes of higher order curves before embarking on their use in fitting data. In fact, the plotting facility presents these quite nicely, especially if "inappropriate" axes are chosen and extensive extrapolation of the curve is visible on the screen. I t would he an improvement if the student were directed in some organized way in the choice of least squares analysis options. Almost all the documentation for the procram is oresented in the manual that acrompaniec rhe rllik. It present5 a clear and orcurate desrr~ptimof the upemtion of the program. The r,mpuler presentation would be improved and made more tractable if some of the information from the manual were reiterated on the screen a t appropriate places. Although the manual has no index, it is well orranized ~.~ and soecifie information can be found, u,hen n p e d 4 , with pare. 'l'hc manual presents an rxcrllrnt guide for the instructor, proposing possible applications but not forcing a particular approach. The instructor has plenty of scope t o express individual creativity in the classroom and laboratorv useof the oroeram. However, the . orneram k s e ~ fcannot be listed or altered in-
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perimental data and questions that bath direct the student and test understanding of the techniques. The graphical analysis program is ready for operation as it stands unless data for student use are to be read from the disk. No soecial equipment IS w q u i r ~ dThe pmgram has rhe facility tu pmvidr hard copy of dsts liitsand graph+ as u built-ln feature. lnformatim ~~~~~~
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(Continued on page A3241
A e v i e w e d in this Issue Reviewer Glenn E. Palmer Dennis Sievers
DavidR. Dice. Graphical Analysis
D. L. Scott Anne M. Searer Donald Foster Mullica and J a m e s L. McAtte. Jr. George D. Sturgeon
Robert J. Ouelene, Microchem
T. Sanderson, Polar Covalence Monographs Titles of Interest
Volume 61
Number 12
December 1984
A323 A324 A325 A326
A326 A327 A327 A328
A323
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