Draftsmans displays for contingency tables using a full-screen, scrollable APL2 spreadsheet input/output editor with application to the PERSEREC database of Special Background Investigation

Abstract

A full-screen, scrollable spreadsheet-like editor written in the APL2 language is described for inputting, examining and outputting data. Mixed numeric and character arrays can be read into or read out to formatted DOS files (ASCII) or comma delimited DOS files. Alternatively a bulk mode input facility allows for rapid direct data entry, or data can be examined and edited cell-by-cell in the usual way. Columns, rows or blocks of data can be highlighted in a chosen color, shadowed, moved or copied. In addition APL functions entered on the command line can use the blocks as input or output. A facility for coding missing values is also provided. Major-to-minor (lexicographic) sorts can be performed on selected columns, and conditional or unconditional frequency tabulations and cross-tabulations of selected columns can be performed. Output is obtained as a new spreadsheet, or equivalently, as an APL2 matrix. In particular, two-way cross-tabulations of multiple columns are laid out in the spreadsheet like draftsman plots to facilitate investigation and explanation of multivariate categorical data. No numerical coding of the data is needed.