Correction: The quality of physical activity guidelines, but not the specificity of their recommendations, has improved over time: a systematic review and critical appraisal

The authors noted some errors in the manuscript that require correction. They are as follows: In the Results section, in the second paragraph under Practicality and specificity of recommendations, the third sentence should read as follows: “However, recommendations from guidelines developed by professional societies, governmental agencies, or an ad hoc working group or task force tended to be more practicable than recommendations written by other types of nonprofit organizations.” In the Results section, under the first paragraph under Year of publication, the second through fourth sentences should read as follows: “There was a modest improvement of 11.3 percentage points in the Rigor of Development domain and of 9.5 points for Stakeholder Involvement.Marked improvement over time was observed for Editorial Independence (change of 49.8 percentage points). Statistically significant correlations between the year of a guideline’s publication and its performance as assessed with AGREE II were found for Stakeholder Involvement (ρ = 0.223; p < 0.05) and Editorial Independence (ρ = 0.567; p < 0.001).” Figure 2 and Supplement 5 are presented below in their corrected forms.