The Relationship Between Word Frequency and Reading Vocabulary Using Six Metrics of Frequency

Abstract

The relationship between word frequency and reading vocabulary was investigated, with particular attention to the lognormal model of word frequency distribution and the concept of family frequency. The effects of grade, ability, and sex on word knowledge were also investigated. Subjects, 576 fourth through twelfth grade students, completed an 86-item, multiple-choice vocabulary test. The words were arranged on six different metrics representing two indexes of frequency (individual form frequency, family frequency) combined with three methods of grouping and scaling words (arithmetic groupings employing a proportional scale, logarithmic groupings employing a proportional scale, logarithmic groupings employing a logitized scale). Results of the blocking variables indicated predictable and reliable (p > .01) differences due to grade and ability but none due to sex on each of the metrics. Results of the variable of major interest, frequency, indicate that when groups of words are considered and the logarithmic groupings are used that employ either the proportional scale or the logitized version of that scale, both individual form frequency and family frequency are excellent predictors of word knowledge. Results further indicate that the metric of family frequency coupled with the logitized logarithimic scale give the simplest account of these data. The predictive value of the lognormal model and approaches to refining the concept of family frequency are discussed. © 1987 Taylor & Francis Group, LLC.