Master of Science
Walter H. Carter, Jr.
One of the most important tools of the applied statistician is the digital computer. It is natural, therefore, for the instructor in applied statistics to want his students to become familiar with the use of computers. If his students are going to get actual experience in using a computer for statistical analysis, he often has only two alternatives. The students can be required to write their own statistical programs or they can use programs already available through a computer facility.
If the course is to be taught such that each student is responsible for his own programs, the instructor must either require that the students have previous programming experience or he must be prepared to spend a portion of his class time teaching a programming language. Neither of these seem to be satisfactory. First, to make knowledge of programming a prerequisite will often reduce the number of people interested in the course. Many students, who would otherwise enroll, might be completely unfamiliar with programming and have no real interest in becoming programmers. To spend a portion of the class time in teaching a programming language and associated programming techniques would often mean that the emphasis of the class could easily shift from the statistical methods to computer programming. This would result in a significant reduction in the enount of nnteriel the class could cover.
The alternative to having each student write his own programs is to use prepared programs available through a computer facility. In most instances, this would mean that each time a student wished to use the computer for a statistical analysis he would have to prepare the data for card input, send the cards to the computer facility, wait, and finally have his results returned. Again either the instructor would have to assign a particular program and would lead the class through the data preparation or he would expect each student to be responsible for reading the program documentation and preparing the data for himself. In many statistical analyses the investigator might wish to run several different programs. For each of these the student might have to review the relevant documentation, punch a new set of data cards and wait. Unfortunately, rather then repeat this procedure several times a student may become satisfied with running only the primary analysis without spending time, for instance, verifying the underlying assumptions.
An example of the type of situation which might indicate several computer run; would be data on which an Analysis of Variance is to be performed. Consider the problem of a student who has data from patients being treated with several different drugs. He wished to test the null hypothesis of no significant differences between the treatment means. He night first wish to run I Bartlett's test for homogeneity of variances. If transforms are necessary on the data he will wish to try them. If he is satisfied that the variances are not significantly different, he will compute the Analysis of Variance possibly following that with Duncan's multiple range test. Since each method is probably done by a different program, the date might have to be completely punched three or four different times. Rather than doing all the extra work the student might simply run the Analysis of Variance and be satisfied with a less than a complete data analysis.
The problems introduced here give the necessary background for the discussion of the APL Statistical System which follows. This discussion is divided into three sections. The first section includes two chapters and discusses broadly the APL Statistical System characteristics which contribute to overcome some of the problems involved in utilizing a computer in statistical instruction. The second chapter describes two basic utilization: of the Statistical System.
The second section describes the computer hardware configuration on which the system is currently being implemented. It also describes some of the important characteristics of the programming language used. A description of the actual statistical System with a list of the statistical methods which are available to the user is also included in the third chapter.
The third section is actually a user's manual giving the operating procedures for the system, an explanation of the keyboard, data entry, and s few of the basic APL operators. To make it an independent part of the thesis so that it may be used alone as a manual, s more complete description of how to use each of the statistical methods is given. For each method an example is shown which can be verified in most cases by the reference source listed in the example. A complete program listing of all the programs, or functions, used in this system can be found in the Appendix.
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