bake_followup_spline: Bake fixed knots into any 'ns(followup, df = N)' term in...

In SEQTaRget: Sequential Trial Emulation

Bake fixed knots into any ns(followup, df = N) term in params@covariates

Description

splines::ns() recomputes knots from whatever data it sees, so without fixed knots the basis at prediction time differs from the basis used at fit time. This helper rewrites every ns(followup, df = N) token in params@covariates to an explicit ns(followup, knots = c(...), Boundary.knots = c(...)) computed once from the full expanded followup column. The result is a formula whose model.matrix output is invariant to the row subset passed in.

Usage

bake_followup_spline(params)

Details

Returns the original covariates string unchanged when no ns(followup, df = ...) token is present (e.g. user supplied custom covariates that already specify knots).

SEQTaRget documentation built on May 21, 2026, 9:07 a.m.