Guide
MDS Data: Two Datasets, Two Different Questions
The Minimum Data Set is the clinical assessment every certified nursing home completes for each resident. CMS publishes it aggregated to the facility, and it publishes it twice: once as scored quality measures, and once as frequency distributions of the individual assessment items. Both are called MDS data, they answer different questions, and mixing them up is the usual reason two people quote different numbers for the same facility.
The two files
| File | What it answers |
|---|---|
| Quality Measures 18 scored measures — falls, pressure ulcers, antipsychotics, weight loss, catheters | How is this facility performing? |
| MDS Frequency Response distributions for individual assessment items, several hundred per quarter | What is this facility’s resident population like? |
Both are published quarterly on data.cms.gov and key on the facility CCN. The frequency file is far larger: a single quarter carries several hundred assessment items per facility.
What the measures tell you
- Fifteen long-stay measures, three short-stay
- Different populations and different denominators, so the two sets are not comparable to each other.
- Nine of the eighteen feed the star rating
- The rest are published but not scored. A weak measure does not always move the rating.
- Scores are four-quarter rolling averages
- A measure period reads like 2025Q2-2026Q1, so one bad quarter keeps affecting the average for a year.
Going deeper
- Nursing home data: what exists and where it comes from
- How the CMS Five-Star rating works
- Nursing home deficiencies and F-tags
Both files, on one record
SNF Insights carries the quality measures and the item frequencies alongside staffing, survey history and financials, so a measure can be read next to what caused it.
Request a demoMeasure counts reflect the CMS files as of August 2026 and change when CMS revises the measure set. SNF Insights is independent and is not affiliated with or endorsed by CMS.