{{Short description|Measure in clinical research}} alt=Illustration of two groups of sixteen: one exposed to treatment, and one unexposed. Exposed group has four individuals with an adverse outcome. Unexposed group has eight individuals with an adverse outcome.|thumb|The group exposed to treatment (left) has 1/4 or 25% absolute risk of an adverse outcome (dark). The unexposed group (right) has 1/2 or 50% absolute risk of an adverse outcome.
'''Absolute risk''' (or AR) is the probability or chance of an event. It is usually used for the number of events (such as a disease) that occurred in a group, divided by the number of people in that group.<ref name="IEA Dictionary of Epidemiology">{{cite book|editor-last1=Porta|editor-first1=Miquel|title=A dictionary of epidemiology.|date=2014|publisher=Oxford University Press|location=Oxford|isbn=9780199976720|edition=Six|url=http://irea.ir/files/site1/pages/dictionary.pdf|accessdate=11 November 2017}}</ref>
Absolute risk is one of the most understandable ways of communicating health risks to the general public.<ref name="Trevena 2006">{{cite journal |last1=Trevena |first1=LJ |last2=Davey |first2=HM |last3=Barratt |first3=A |last4=Butow |first4=P |author-link4=Phyllis Butow |last5=Caldwell |first5=P |date=February 2006 |title=A systematic review on communicating with patients about evidence. |journal=Journal of Evaluation in Clinical Practice |volume=12 |issue=1 |pages=13–23 |doi=10.1111/j.1365-2753.2005.00596.x |pmid=16422776 |doi-access=free}}</ref>
In difference to absolute risk, the relative risk (RR) is the ratio of the probability of an outcome in an exposed group to the probability of the outcome in an unexposed group.
==See also== * Absolute risk reduction * Relative risk reduction
==References== {{Reflist|30em}}
==Further reading== * {{cite book |last1=Woloshin |first1=Steven |last2=Schwartz |first2=Lisa M. |last3=Welch |first3=H. Gilbert |authorlink3=H. Gilbert Welch |year=2008 |title=Know Your Chances: Understanding Health Statistics |language=en |location=Berkeley (CA) |publisher=University of California Press |PMID=23469386 |url=https://pubmed.ncbi.nlm.nih.gov/23469386/ }}
Category:Medical terminology