Abstract
Forty-six studies of basal gastric secretion each lasting 6 hours, were carried out in 23 patients with duodenal ulcer. Variations in hourly total acid and pepsin output from patient to patient were significantly greater than those on different occasions in the same patient. A significant correlation was found between the initial hour level and the subsequent four hourly levels. In addition, the initial hour level also affected the pattern of the subsequent hourly levels. When comparative observations of a quantitative character of a test procedure on basal gastric secretion are made, a concept of any real differences in secretory response can only be formed from a knowledge of the relationship existing between the initial hour level and that after test procedure of the gastric secretion. The use of covariance analysis with the initial hour level as concomitant variable removes the variations of the averages of subsequent four-hour levels from patient to patient. When the absolute values of hourly total acid and pepsin output were expressed as percentages of the initial hour level, variations from patient to patient also became nonsignificant. However, the use of percentage values would be simpler to apply than that of covariance analysis. Thus, the use of variance analysis on percentage values or covariance analysis on absolute or percentage values may permit a more precise evaluation of the results obtained in many patients. Submitted on March 7, 1957