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. Positive confounding (when the observed association is biased away from the null) and negative confounding (when the observed association is biased toward the null) both occur. Confounder: an extraneous variable that wholly or partially accounts for the observed effect of a risk factor on disease status..