Cytoprotection is defined as an ability of pharmacologic agents, originally PGs, to prevent gastric and intestinal mucosal injury produced by a variety of ulcerogenic agents (eg, aspirin, indomethacin, bile acids) and by necrotizing agents (eg, boiling water, absolute alcohol, 0.6 mol/L HCl, 0.2 mol/L NaOH).
Definition of systematic error. : an error that is not determined by chance but is introduced by an inaccuracy (as of observation or measurement) inherent in the system.
Bias: A systematic error in the design, recruitment, data collection or analysis that results in a mistaken estimation of the true effect of the exposure and the outcome. Confounding: A situation in which the effect or association between an exposure and outcome is distorted by the presence of another variable.