RALSA: Design and Implementation

International large-scale assessments (ILSAs) provide invaluable information for researchers and policy makers. Analysis of their data, however, requires methods that go beyond the usual analysis techniques assuming simple random sampling. Several software packages that serve this purpose are available. One such is the R Analyzer for Large-Scale Assessments (RALSA), a newly developed R package. The package can work with data from a large number of ILSAs. It was designed for user experience and is suitable for analysts who lack technical expertise and/or familiarity with the R programming language and statistical software. This paper presents the technical aspects of RALSA—the overall design and structure of the package, its internal organization, and the structure of the analysis and data preparation functions. The use of the data.table package for memory efficiency, speed, and embedded computations is explained through examples. The central aspect of the paper is the utilization of code reuse practices to the achieve consistency, efficiency, and safety of the computations performed by the analysis functions of the package. The comprehensive output system to produce multi-sheet MS Excel workbooks is presented and its workflow explained. The paper also explains how the graphical user interface is constructed and how it is linked to the data preparation and analysis functions available in the package.