Simpson, JaneAngelo, DeniseBrowne, EmmaKral, IngeMarkham, FrancisO'Shannessy, CarmelVenn, DanielleSebastian DrudeNicholas OstlerMarielle Moser2020-08-112020-08-1123-25 Augu978-1-9160726-0-2http://hdl.handle.net/1885/207398In Australia, language ecologies have become complex, as speakers of Australian Indigenous languages (whether traditional or new contact languages) may be multilingual with different levels of proficiency in different languages. Using the Indigenous language spoken by one's ancestors asserts association with a speech community (past or present). People may be using the language for everyday talk, or they may be using it along with other languages, including standard English, the language of wider communication, or they may be re-learning the language. The speakers may live in the heartlands of their traditional country or they may be living in diaspora communities around Australia. Quantitative data on the location and number of speakers of minority languages is needed for convincing governments of where they should direct resources for education, interpreting and service provision. Some data on language use (direct or inferred) is obtainable from the five-yearly Census of Population and Housing surveys by the Australian Bureau of Statistics (ABS). The language questions in these studies lead to some unexpected findings that vary in plausibility when compared with case studies of particular communities. A data review of this source is provided, considering the strengths and weaknesses with respect to what has been observed in several case study communities. We propose ways for assessing quantitative results, and combining them with case studies of individual communities to produce more reliable models of language change.We gratefully acknowledge the support of the ARC Centre of Excellence for the Dynamics of the Language, the Centre for Aboriginal Economic Policy Research and the Department of Communication and the Arts.application/pdfen-AU© 2018 The Author(s)http://creativecommons.org/licenses/by-nc/4.0/20182020-04-19Creative Commons License CC-BY-NC (Attribution-NonCommercial)