“…To date, however, most literature has focused on MLMs for univariate responses, with the notable exception of Pfeffermann and Sverchkov (2019), who considered a multivariate hierarchical model, in the context of estimating multiple characteristics at small area level under nonignorable (NMAR) nonresponse. Veiga et al (2014) also extended the approach of Pfeffermann et al (1998) to multivariate MLMs in the context of longitudinal complex survey data. Multivariate responses emerge both as a means to handle longitudinal measurements on the same units, as considered by Veiga et al (2014), and in the context of educational assessment studies where students are assessed using two or more proficiency tests, with each test providing a proficiency score.…”