TISS-28 (Simplified Therapeutic Intervention Scoring System) was constructed from a random sample of 10,000 records of original TISS-76 items in 1996 to describe nursing activities. The simplified TISS-28 explains 86% of the variation in TISS-76 and can therefore replace the original version in the clinical practice in the ICU. Per shift, a typical nurse is capable of delivering nursing activities equal to 46 TISS-28 points.