Cross-Basis Construction

Construct cross-basis matrices for Distributed Lag Non-Linear Models in R.

Updated Mar 7, 2026
One-click install
npx skills add https://github.com/ntluong95/agent-skills-statistics --skill cross-basis-construction
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: Cross-Basis Construction
Source: https://github.com/ntluong95/agent-skills-statistics/tree/main/skills/dlnm/crossbasis
Command: npx skills add https://github.com/ntluong95/agent-skills-statistics --skill cross-basis-construction

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill simplifies the complex process of constructing bi-dimensional cross-basis matrices, which are essential for modeling both exposure-response and lag-response relationships simultaneously in Distributed Lag Non-Linear Models (DLNMs).

Core Features & Use Cases

  • Flexible Basis Functions: Supports various basis functions like natural cubic splines (ns), B-splines (bs), and penalized splines (ps) for both exposure and lag dimensions.
  • Optimized Knot Placement: Provides guidance on placing knots effectively for both exposure (e.g., percentiles) and lag (e.g., log scale) dimensions to avoid overfitting.
  • Key Argument Guidance: Explains crucial arguments like lag, argvar, and arglag for accurate model specification.
  • Use Case: When analyzing the impact of daily temperature on mortality, use this Skill to define how temperature variations and their effects over subsequent days are modeled.

Quick Start

Construct a cross-basis matrix for a daily temperature exposure with a 21-day lag, using natural cubic splines for both dimensions with appropriate knot placements.

Frequently Asked Questions about Cross-Basis Construction

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I build a cross-basis matrix for a distributed lag non-linear model in R?

To build a cross-basis matrix for a distributed lag non-linear model, use the dlnm::crossbasis() function in R to define basis functions and knot placements for both exposure and lag dimensions simultaneously.

When should I use cross-basis functions for exposure-lag-response relationships?

Use cross-basis functions for exposure-lag-response relationships when you need to model the bi-dimensional impact of a predictor, such as daily temperature, and its effects across subsequent days simultaneously.

What is the best way to place knots for natural cubic splines in DLNM?

The best way to place knots for natural cubic splines in DLNM is using percentiles for the exposure dimension and a log scale for the lag dimension, which helps avoid overfitting the bi-dimensional relationship.

Can I use penalized splines or B-splines for both exposure and lag dimensions in dlnm?

Yes, you can use penalized splines or B-splines for both exposure and lag dimensions in dlnm, as the function supports various basis types including ns, bs, and ps for flexible model specification.

How do I specify the lag period and arguments for a DLNM cross-basis?

To specify the lag period and arguments for a DLNM cross-basis, define the lag length and use the argvar and arglag parameters to pass specific basis function and knot placement guidance for accurate modeling.