In Programme for International Student Assessment (PISA), students were asked if the language spoken at home most of the time is the language of assessment, another official national language, other national dialect or language, or another language. The responses were then grouped into two categories: the language spoken at home most of the time is different from the language of assessment, from other official national languages, and from other national dialects or languages, and; the language spoken at home most of the time is the language of assessment, other official national languages, or other national dialects or languages.