# Method

Source: CMS Doctors and Clinicians National Downloadable File, fetched 2026-09-15.

- Physical therapists: pri_spec PHYSICAL THERAPIST IN PRIVATE PRACTICE (96,434 NPIs; 86,479 linked to a group via org_pac_id).
- A group is an org_pac_id. Groups are mapped to a brand by a regular expression on the legal name (Facility Name); the patterns are in tools/report_pt_chains_facts.py. Unmatched groups keep their legal name.
- A therapist counts once per brand. "Also in other group" counts therapists of a brand who also appear under an org_pac_id outside that brand.
- States: distinct practice states of the brand's rows.
- The file covers clinicians enrolled in Medicare. Therapists who do not bill Medicare are not in it.