“Why does NIH use percentiles for investigator-initiated R01 applications instead of overall impact score?”

Left alone, study sections tend to give applications increasingly better scores through a phenomenon called “score creep.” When scores are overly clustered in the exceptional range, it becomes impossible to discriminate among applications.

Further, various study sections may apply NIH review criteria differently, scoring either more harshly or more favorably than other study sections.

Percentiling counters these tendencies by ranking applications relative to others scored by the same study section. Altogether, percentiling makes review fairer to applicants.

Learn more at Understand Paylines and Percentiles.