The need to establish the department of statistics was realised during the preparatioin of the first theree year (1979-81) plan for economic and social development of Zanzibar.It was felt then that the unit would not have capacity to produce statistical data and information required to inform and underpin the development plan. Since statistics has not been a union matter, the department was solely responsible for statistics in Zanzibar
In 1999, the statistics act was revised to make provision of statistics data and information more effective and response to user need. The Office of Chief Government Statistician (OCGS) was established as an autonomous body corporate by statistics act No. 9. of 1999. The act also provides for an advisory board to advise the OSGC and the minister on matters related to statistical information
Collection, processing and dissemination of statistical information
Standardization of statistical methods, classifications and definitions
Technical cooperation programme
Coordination of international statistical programmes and activities
Out of its functions, The Office of Chief Government Statistician Zanzibar has:
"To become a 'centre of excellence' for statistician production and for promoting a culture of evidence-based policy and decision-making"
"To coordinate production of official statistics, provide high quality statiscal data and information and promote their use in planning, decision-making, administration, governmance, monitoring and evaluation."