ABSTRACT
The most familiar device for presenting relationship is the pedigree or family tree, the chart of the relationship between ourselves and our "relatives". This analogy is particularly appropriate because it distinguishes mere association or correlation from causal relationship, and distinguishes, further, between different forms of relationship. A genealogical tree is helpful not merely in disentangling all the relevant conditions possibly influencing the point at issue, but also in devising indices and index ratios to measure an otherwise non-measurable issue, and to make certain of and test the adequacy and non-ambiguity of such indices. The analogy of cause and effect relations with genealogical family relations has clearly two important limitations. The method of the indentation table setting forth possible causes and results and their exact relationship may be further extended to distinguish the different types of causation that are for the moment surmised of the specific situation dealt with.
