Absolute Risk: The probability that an event will occur in a given population.
Absolute Risk Reduction, or Risk Difference: The proportion of
untreated individuals who experience an adverse event minus the
proportion of treated individuals who experience it.
Alpha Error or Type 1 Error: A false result that occurs when the null
hypothesis is rejected but is actually true.
Beta Error or Type II Error: A false result that occurs when the null
hypothesis is not rejected but is actually false.
Bias: Systematic error of study results deviating from the truth.
Bonferroni Approach or Correction: A technique to correct for multiple
comparisons that adjusts the alpha error by dividing it by the number
of different hypotheses tested.
Case Control Study: An observational study of persons with a condition
of interest (“cases”) and a suitable control group without the
condition, where the past history of exposure to a suspected risk
factor is compared between cases and controls.
Clinical Practice Guideline: A systematically developed document that
aims to assist in guiding diagnostic, management, and treatment
decisions and criteria for health conditions.
Cohort Study: A study design in which deﬁned population groups
whose exposure or lack of exposure to possible risk factors is known
are followed over time to determine the influence of these factors on
disease or other outcome.
Retrospective Cohort Study: A cohort study conducted with
reconstruction of information about past exposures.
Prospective Cohort Study: A cohort study conducted prospectively
with exposure information obtained before the outcomes are