Systems measures of word use and differential diagnosis

This paper presents findings on the power of two systems measures of word use to discriminate four patient groups. The first is the slope of accumulated entropy or complexity of the sample (known to be logarithmic over time). The other is the average Poisson rate for the use of new words (known to be a Poisson process). The four groups consisted of cancer, depressed, paranoid, and somatization patients. The two word measures discriminate the first three groups from the fourth. There is evidence that larger samples will identify a similar discriminator for each of the first three groups from one another. The results are discussed in terms of how these methods may offer fresh insight into the relationship between language use and psychopathology.