Circular analyses of dates on patients with gastric carcinoma.

Dates have great importance in cancer diseases. However, the date variables themselves are not analyzed. This study aims to evaluate the descriptive statistics of diagnosis, operation, and last examination dates in gastric carcinoma patients by circular analysis methods. Totally 502 gastric carcinoma patients were enrolled in the study. The mean month of diagnosis date was found in nearly November (∼10.86) for females and May (∼5.17) for male patients. The mean month of operation date was found March (∼3.24) for females, and July & August (∼7.79) for males. The mean month of the last examination date was found as February & March (∼2.61) for females, and May (∼4.85) for males. Moreover, the mean day of the week for diagnosis date was found Thursday (∼5.50) for both female and male patients. The fitting of distributions of all variables was checked, also, according to von Mises, Rayleigh, and Kuiper's tests. When the days and months were analyzed by classical descriptive statistics, the results were obtained completely different from the circular analyses results. Therefore, the dates and times should be analyzed in certain diseases to give an idea for physicians.