CRANV2 Main test results chapter Cyril Cleverdon Michael Keen Cranfield An investigation supported by a grant to Aslib by the National Science Foundation. Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. - 159 - Section 8 Controlled terms Recall devices The investigations on the controlled term languages were carried out on two sets of questions and two collection sizes: the 42 questions (subset 2) searched on the 200 document collection (subset i), and the 77 questions (subset 7) searched on the 350 document collection (subset 2). Six recall languages were tested, and the effect of each recall device is seen in the tables and plots given in Figs, 4. 800TP 4.805TP, tested with a search rule A. A plot of the six curves is given in Figure 4.806P. The recall devices are shown in Fig. 2.7 (p, ll) Search Rules Further comparison ef the six index languages is given with the tests made using Search Rule E on both the 42 questions with the 200 document collection and the 77 questions with the 350 document collection. The results are presented in Figs. 4.810TP - 4,815TP and 4,820T - 4,825T, with plots covering the various index languages as Figs. 4.816P and 4.826P. With Search Rule E all the combinations of acceptable terms were selected for each coordination level. Examples of search formulations for a number of questions are given in Appendix 8.1. Tests with Search Rule 17' were done on index languages III. 5.a and II1.6.a with 42 questions on the 200 document collection. This search was superimposed on Search E, and the results are presented at the various coordination levels according to the number of basic terms as apart from related terms. Thus, at a coordination level of 4, the tables (Figs. 4.850T and 4.851T) show the results when all terms were basic terms, where one term was a related term, where two terms were related terms and so on. It is obvious that when all the terms are basic terms, then the results must be the same as for index language III. l.a With Search E; when all the terms are related terms, then the results must be the same as for the corresponding index language with the basic Search E. Therefore in the plot 4.850P, the two main curves represent index languages III.l.a and III. 5.a with Search E and in Figure 4. 851P the main curves represent index languages III.l.a and III. 6.a, again with Search E. Tile additional results obtained with Search F now produce a series of secondary curves at each coordination level which span the main curves. Precision Device The precision device of weighting was tested, in which search questions were weighted and tested on the most exhaustive index language, using the weights assigned in indexing. Figs. 4.830TP and 4.831TP give results for languages III.l.a and IIi.6,a respectively, and in the plots a comparison is made of the weighted and unweighted searches, carried out with search rule E.