Saxon's Genitives
Saxon’s genitive is the English possessive form that marks a close relation—ownership, authorship, association, or time/quantity—by adding ’s to a singular noun or irregular plural, and ’ after a regular plural ending in -s.
Examples:
The trial’s primary endpoint was overall survival (OS).
Five years’ follow-up showed sustained remission in the cohort.
Core Formation Rules
Singular noun: Adds the patient’s consent form; the liver’s microarchitecture
Regular plural ending in -s: add ’ only the patients’ outcomes; the controls’ demographics
Irregular plural (no final -s): add ’s The Children’s hospital; the mice’s survival curves
Names ending in s: either ’s or ’ (be consistent with your house style) Hodgkins’s contribution / Hodgkins’ contribution
Compound/phrases: add to the end of the whole phrase The principal investigator of Site 3’s signaturePrefer a cleaner revision if heavy: the signature of the principal investigator at Site 3.
’s or “of the”? Quick rule
Uses for people, organisations, and time/measure: The surgeon’s note; the sponsor’s response; two weeks’ washout.
Use for technical or physical properties, or when the phrase is long: The viscosity of the polymer, the porosity of the scaffold.
Five short caselets
Clinical research
The trial’s primary endpoint was OS.
Agency terms also take: The DSMB’s recommendation; the sponsor’s safety letter.
For properties, preference: The sensitivity of the sequencer improved after recalibration.
Laboratory methods
The pipette’s calibration drift exceeded 1%.
For physical parameters, the surface tension of the solution decreased with temperature, reads smoother than the solution’s surface tension….
Animals: The mice’s survival curves separated after day 10 (or recast to survival curves for mice…).
Hospital quality
The hospital’s antimicrobial policy reduced C. difficile rates.
Avoid chains like the oncology unit’s nursing team’s rota; write the oncology nursing rota or the rota of the nursing team in the oncology unit.
Regulatory/quality
The application’s Module 3 included updated specifications.
The manufacturer’s CAPA closed Repeat Deviation-12.
For labels: Both the label’s storage instruction was revised to 2–8 °C and the storage instruction on the label… are fine—be consistent.
Public health/logistics
Time/quantity genitives are standard: Five years’ follow-up; two weeks’ oxygen stock; a month’s washout.
With plural units, the apostrophe follows s: years’, weeks’.
Medical eponyms (important style point)
Use non-possessive disease names in formal medical writing: Parkinson's disease, Alzheimer's disease, Crohn disease.
You may still use ’s when referring to people/authorship: Alzheimer’s 1907 paper; Parkinson’s description.
Joint vs separate possession
Joint (one thing shared): Abbott and Lilly’s co-development plan.
Separate (different things): Abbott’s and Lilly’s phase 3 programmes.
Acronyms and initialisms,
The on FDA’s guidance
the ICU’s capacity
AIIMS’ ethics board (or AIIMS’s ethics board).
Choose one pattern and apply it everywhere.
Common slips and quick fixes
Plural confusion: patients’ vitals (many patients), not patients’ if plural intended.
Dropped apostrophe in time phrases: two weeks’ run-in, not two weeks run-in.
Heavy chains: break or switch to of.
Overusing’s for measurable properties: prefer of.