Survey-robust uncertainty quantification in generalised additive models for location, scale, and shape

Conventional mean-only regression models are often too restrictive for the analysis of complex survey data, where interest frequently extends beyond the conditional mean to other aspects of the response distribution. Generalised additive models for location, scale and shape (GAMLSS) provide a flexible framework by allowing all distributional parameters to depend on covariates. However, existing model-based and model-robust standard errors fail to account for complex survey designs and can substantially underestimate the variability of regression parameter estimates. We propose a linearisation-based sandwich variance estimator that incorporates the survey design while remaining computationally efficient. Using a simulation study based on synthetic survey data, we demonstrate that the proposed estimator provides accurate standard error estimates and reliable confidence interval coverage for all distributional parameters, while offering a computationally efficient alternative to replication-based methods. We further illustrate the practical utility of the approach through a re-analysis of data from the 2019/20 Rwanda Demographic and Health Survey (DHS).