The Enduring Evolution of the P Value

Mathematics and statistical analyses contribute to the language of science and to every scientific discipline. Clinical trials and epidemiologic studies published in biomedical journals are essentially exercises in mathematic al measurement. 8] ] Based on automated text mining of more than 12 million MEDLINE abstracts and more than 800 000 abstracts and full-text articles in PubMed Central, the authors found that a greater percentage of scientific articles reported P values in the presentation of study findings over time, with the prevalence of P values in abstracts increasing from 7.3% in 1990 to 15.6% in 2014. Among the abstracts and full-text articles with P values, 96% reported at least 1 "statistically significant" result, with strong clustering of reported P values around .05 and .001. In addition, in an in-depth manual review of 796 abstracts and 99 full-text articles from articles reporting empirical data, the authors found that P values were reported in 15.7% and 55%, respectively, whereas confidence intervals were reported in only 2.3% of abstracts and were included for all reported effect sizes in only 4% of the full-text articles. The authors suggested that rather than reporting isolated P values, research articles should focus more on reporting effect sizes (eg, absolute and relative risks) and uncertainty metrics (eg, confidence intervals for the effect estimates).