Last update:
09-Oct-2018

Readers of scientific papers are affected by the way in which the authors present the results of their studies. Appropriate presentation of the results of studies is necessary for the readers to understand the conclusions, and thus improves the quality of published papers. Measures of effect denote the relationship between determinants and outcomes. Authors may overestimate or underestimate the true size of an association, depending on the choice of the measure of effect. This inherent disadvantage of measures of effect could be eliminated by presenting all of the possible measures of effect in a study. In such a case, the readers could understand more fully the results of a study, and draw the correct conclusions. A great variety of measures of effect can be calculated in studies. Measures of effect regarding incidence of outcomes, which are extremely important, are discussed in the present article. In particular, the terms absolute incidence reduction, relative incidence reduction, incidence ratio, and number needed to treat, will be discussed. Absolute incidence reduction and number needed to treat are dependent on the incidences in the compared groups, while relative incidence reduction and incidence ratio are stable and independent of the incidences in compared groups.

Key words: Absolute incidence reduction, Incidence, Incidence ratio, Measures of effect, Number needed to treat, Relative incidence reduction.