FREQUENCY STABILITY OF KENT-ROSANOFF WORDS

Summary.-Shifts in the frequencies of the Kent-Rosanoff words are described by applying a lognormal model to distributions resulting from the use of two frequenq counts, the Thorndike-Lorge count and the Kucera-Francis count. The former's categorization limits consideration to 44 words which had frequencies in, or lower than, the A category (50-99 words per million) of T-L. The predominant shift is toward lower frequencies of occurrence in the latter count. The amount of shift toward lower frequencies increases as the Thorndike-Lorge frequenq of the words decreases. The average shift is 14 words per million. The findings suggest a severe Limitation on the generalizabilicy of experimental results which have used the Thorndike-Lorge source to control the frequency characteristics o! the Kent-Rosanoff words. The frequencies of occurrence of the Kent-Rosanoff words (K-R) have been manipulated or controlled in studies of verbal associations and learning. Frequency characteristics have been measured using the Thorndike-Lorge (1944) count (T-L) . A recent frequency count is available for judging the frequenq characteristics of the words (Kucera & Francis, 1967). It is desirable to compare the frequencies of occurrence of normative words in the two counts in order to assess the effects of shifting usage from the Thorndike-Lorge to the Kucera-Francis count. A lognormal model, which provides a satisfactory description of frequency distributions for grammatically selected normative words (Bowen, 1971a, 1971b) and unselected words (Carroll, 1967), will be used here as one technique for describing the temporal stability of the Kent-Rosanoff frequencies. Method.-The first methodological step was to determine the goodness of fit of a normal distribution to distributions based upon the common logs (@) of the ThorndikeLorge and Kucera-Francis frequencies for 100 Kent-Rosanoff words. Both frequencies were converted to q units. Words in the A category of the Thorndike-Lorge source, with frequencies between 50 and 99 words per million (w.p.m.), were assigned a value of @ -4.15, for the midpoint of their class interval. All words in the AA category of this source, with frequencies of 100+ w.p.m., were assigned the @ value, -4.00, for 100 w.p.m. Unit-normal deviates lor cumulative proportions of words were plotted against @ for the Thorndike-Lorge and Kucera-Francis frequencies. The cumulative proportion of 1.00 was assigned a normal deviate of 3.70. The lognormal model provides a good fit to the original frequenq distribution if there is a linear relationship between the normal deviates and @. Frequenq shifts were described by subtracting Thorndike-Lorge frequencies from Kucera-Francis frequencies and averaging the results. Resu11s.-Fig. 1 presents 9 plotted against the unit-normal deviates for cumulative proportions of words. The Pearson product-moment correlation coefficient between @ and the deviates is .85 for Thorndike-Lorge data and, for Kucera-Francis data, r = .98. The Kucera-Francis frequencies are evenly distributed across the frequency range but, for the Thorndike-Lorge data, 44 words lie between @ = -5.10 and @ = -4.15 and 56 words fall at @ = -4.00. These cecsoring and truncation effects, produced by the Thorndike'The writer gratefully acknowledges the support of a Research Grant and Faculty Research from the Research Foundation of the State University of New York. Also F:L%-%fged with gratitude is the assistance of J. W. Strauch.