This paper represents a systematic treatment of the potential dual effect of the context in which an essay is reread and the previously assigned score (value) of that essay on the subsequently assigned essay score. This effect is theorized in a formula referred to as "essay score change" (ESC). Examples of the possible utility of the ESC index are outlined. Tentative hypotheses for investigating and interpreting possible essay score change in light of potential dual effects of context and score level are discussed. (23pp.)