STI reliability is judged against its 0.15 category step size

Evidence

The step size for the categories is 0.15. If a measurement of STI is repeated several times, and if the standard deviation is notably smaller than 0.15, the STI measurement and its interpretation can be considered to be reliable. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2431

Categorization

• DEFINE: Specifies the quality-category granularity used to judge measurement repeatability.