A-sa-bsm.qmd

## SA: STS and MSTS {.unnumbered #a-sa-bsm}

Basic Structural models (BSM) allow to decompose a time series with explicit models for its components ($S$,$T$,$I$) while running pre-treatment in one single step. It also allows to integrate time varying trading-day correction.


## In this Chapter

We will cover how to perform seasonal adjustment using BSM in JDemetra+. 



How to tackle multiple periodicities (with rounded frequencies) in infra-monthly data will be described in the [high-frequency](#a-sa-hf) data related chapter.  

More methodological details will be provided [here](#m-ssf)

## Tools for access

In JDemetra+ Basic Structural Models are only available through [rjd3sts](https://github.com/rjdverse/rjd3sts) package.