Most data sets can be described by a single data matrix, but some have a more complex structure. We briefly mention another type of data called multi-level data.
Each data matrix can be separately analysed.
Household survey
Analysis of the separate data matrices
Difficulties with interpretation
Both group-level and individual-level data matrices can be analysed with the methods described in this e-book, but interpreting the results of the analysis requires a lot of careful thought!
Advanced statistical methods are needed to fully analyse multi-level data.