Review of ((2008)): International Journal of Corpus Linguistics

Abstract

Gries (2008) in this journal reviewed a variety of dispersion measures as well as adjusted frequencies and also proposed a measure for dispersion of elements in a corpus: DP (for deviation of proportions). This measure is computed as described in (i) to (iii) for an element a in n corpus parts. (i) Determine the sizes s1−n of each of the n corpus parts, which are normalized against the overall corpus size and correspond to expected percentages which take differently-sized corpus parts into consideration. (ii) Determine the frequencies v1−n with which a occurs in the n corpus parts, which are normalized against the overall number of occurrences of a and correspond to observed percentages. (iii) Compute all n pairwise absolute differences of observed and expected percentages, sum them up, and divide the result by two. The result is DP, which can theoretically range from approximately 0 to 1, where values close to 0 indicate that a is distributed across the n corpus parts as one would expect given the sizes of the n corpus parts. By contrast, values close to 1 indicate that a is distributed across the n corpus parts exactly the opposite way one would expect given the sizes of the n corpus parts. Table 1 is an example of how to compute DP if there are three equally large corpus parts, and one of these corpus parts contains 2/3 of all occurrences of a, and another part contains the remaining 1/3.