Statistical Methods, Standards and Guidelines 131
The budget committee is formed to facilitate and consolidate budget inputs from all departments and submit to NBS management and later on scrutinized by the Directorate of Finance. The drafted budget is thereafter shared to all staff through Workers Council before submitting to the Ministerial Advisory Board (MAB) for approval and later on to the responsible ministry for funding.
Commissioned Work Apart from Government subvention, the NBS generates its own revenue from commissioned work which forms an important source of internal revenue for NBS.
6.14 GEOGRAPHICAL INFORMATION SYSTEM (GIS)
A Geographical Information System (GIS) is a computer system for capturing, storing, checking,
and displaying data related to positions on Earth's surface and the events that take place on it. A
GIS is an information system designed to work by combining database functions with computer
mapping to map and analyze geographic data. It uses a "layering" technique to combine various
types of data. GIS can show many different kinds of data on one map. This enables people to more
easily see, analyze, and understand patterns and relationships. It may also be considered as a
higher order map.
6.14.1 Objectives and uses of GIS
The main objective of NBS GIS section is to produce accurate and reliable digitized maps that can be used to facilitate census and survey operations, information dissemination, spatial analysis and Master Sample frame development.
6.14.2 Methodology used in GIS
The Census maps which refer as an enumeration area (EAs) are created by the National Bureau of Statistics (NBS) in collaboration with other sectors through provisional of supportive material such as base maps being used by the GIS personnel for creation of enumeration areas. Base maps are produced by the Surveys and Mapping Division of the Ministry of Lands, Housing and Human Settlements Developments that plays great roles during demarcation of EAs maps. Also, other supportive document during the demarcation process is the government notes that describe the National Administrative boundaries at different levels from hamlet to National. The President’s
Statistical Methods, Standards and Guidelines 132
Office, Regional Administration and Local Government (PORALG) provide this important
information.
The implementation of the whole process of map creation activities involve the following
procedures:-
Data capture
All spatial are captured by means of GPS device while non-spatial data are recorded using
developed special form. Additionally, other information including; households, prominent features
such as rivers, mountains, roads, communication towers, etc are important landmarks and their
respective geographical location are captured using GPS as well as to be used in defining the
boundary of created EA. These collected features and other information are used as a guides to
help the enumerator to identify it respective enumeration area during Census/Survey operations.
The demarcation of EAs should satisfy the following requirements in order to conform to the
standards set by the office:
(i)
Boundaries and starting points are clearly identifiable;
(ii)
Boundaries of EAs should not cut across Village Boundaries which is a smallest
administrative level in the country;
(iii)
EAs should not overlap with one another;
(iv)
Each EA should be of a reasonable size (between 60 to 100 Households).
Data Processing
This is a series of operations on data, to retrieve, transform, or classify information. It involves Scanning, Geo referencing, Digitization and Enumeration area (EA's). The map coordinate system of the Census Library is Universal Transverse Mercator (UTM). Most of the data are stored in zone 35 to 37s (Southern Hemisphere). Units are metric (meters). The datum is Arc 960.
Data Output
(a) Enumeration area (EAs) and Supervision area (SA), generally refer to the smallest geographical area from which Census/Survey data are collected. Development of sets of EAs and SAs are stored in PDF format, sized to fit A3 with special layout/templates.
(b) Statistical Maps refer to maps showing the spatial distribution of statistical data. The purpose is to present significant statistical results in terms of their geographic distribution.
Statistical Methods, Standards and Guidelines 133
Thus interest in the current pattern of distribution and also in changes in the patterns that have occurred over time, particularly since the last census/similar survey is considered.
(c) Thematic maps,; A map that focuses on a particular theme or special topic. GIS section Using the census statistics and boundaries in a Geographical Information System (GIS) allows for spatial analysis of the census data and its combination with other non -census geographically referenced data sets. Digitized boundary datasets can be used for: (i) Administrative boundaries maps; (ii) Map production for Population distribution at different level of administration; (iii) Tanzania inter-censual growth rate by Regions; (iv) Tanzania population density by regions; (v) Tanzania Sex ratio by Regions; (vi) Map production for sanitation; (vii) School enrollment maps; (viii) Geo statistical analysis of demographic; (ix) Small area analysis and deprivation studies; (x) Health care research – incidence mapping and analysis; (xi) Provides consultancy when needs arises; and (xii) Historical demographic research and etc.
6.14.3 Reference to applicable standards
All procedures and methods for data collection, processing and map production follow
international standards of map making elements and cartographic aspects.
Datum used: Arc 1960; Geographical Coordinate Systems and/or Projected Coordinate Systems
(UTM).
National Bureau of Statistics
Director General
18 Kivukoni Road
Tel : +255 (0) 22-2122722/3 P. O. Box 796
Fax : +255 (0) 22-2130852 11992 Dar es Salaam
E-mail [email protected] TANZANIA
[Website: www.nbs.go.tz]
Vision “To become a one-stop centre for official statistics in Tanzania.”
Mission “To produce quality official statistics and services that meet needs of national and international stakeholders for evidence-based planning and decision making.”