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MultiSpline

ANALYTICS
Velocity0.0

Spline-Based Nonlinear Modeling for Multilevel and Longitudinal Data

github.com/causalfragility-lab/multispline ↗

MultiSpline went from five functions to a full multilevel spline framework in seven weeks.

splinesmultilevel-modelslongitudinal-datar-packagecran
◆Current state
MultiSpline fits spline-based nonlinear models to multilevel and longitudinal data in R. The package reached CRAN in February 2026 with five functions covering fitting, summary, prediction, plotting and intraclass correlations. Version 0.2.0, seven weeks later, adds cross-classified and nested random-effect structures, automatic knot selection, a multilevel R-squared variance partition, derivative-based interpretation with turning points, model comparison against polynomials, and cluster heterogeneity analysis, while keeping every 0.1.0 call valid.
◆Where it's heading
The arc is a research package being built out into a workflow at speed: 0.1.0 could fit a curve, 0.2.0 can tell you where the curve turns, how much variance each level explains, and whether a spline beats a polynomial at all. Backward compatibility was preserved across that expansion, which suggests the author is building for outside users rather than a single paper. The JOSS submission referenced in 0.1.1 points at academic distribution as the intended channel.
◆Prediction
With the interpretation and diagnostics layers now in place, the next release will most likely extend the supported model families beyond the current lmer and glmer backends.

◆Recent moves

  1. 4mo ago

    Cross-classified and nested structures turn MultiSpline into a framework

    ⚡ SPARK

    The release that converts a five-function fitting package into an estimation, interpretation and diagnostic workflow, without breaking any 0.1.0 call. Everything the trajectory describes as the interpretation layer arrives here at once.

    View source ↗
  2. 5mo ago

    MultiSpline v0.1.1

    DESCRIPTION references, example wrappers changed from dontrun to donttest, and JOSS paper updates. Submission housekeeping between the initial release and the 0.2.0 expansion.

    View source ↗
  3. 5mo ago

    MultiSpline v0.1.0 - Initial Release

    The initial CRAN submission, with five functions covering fitting, summaries, prediction, plotting and intraclass correlations. The baseline against which 0.2.0's expansion should be read.

    View source ↗
  4. 5mo ago

    v0.1.0.1

    Removes build artifacts from the repository, minutes after the initial release tag. Repository hygiene with no user-facing effect.

    View source ↗