Statistical Methods, Standards and Guidelines
113 Existing data which were captured prior to establishment of these procedures for lineage reporting and data quality reporting must be identified as such. In such cases, lineage and quality estimates should only be made when there is some degree of certainty and confidence in this information. Estimated lineage items should be identified as "estimated". Unknown lineage and quality parameters must be listed as "unknown". Any database merging data from more than one source should identify those sources by providing a lineage reference on each one used.
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- Layer Summary Each layer of data collected shall have a Layer Summary file or attribute table attached to the database.
Each user who collects one or more databases will develop and maintain a layer summary form for each layer collected to be attached to the database. This form will describe or provide a reference for the classification, attributes, and attribute coding scheme for each database.
6.0. Census Map Library The main objective of census mapping is to subdivide the country into small Standard Enumeration Areas (EAs), each of which will be assigned a unique identification code on the basis of the country's administrative divisions.
6.1. The demarcation of EAs should be such that they satisfy the following requirements:
a)
Boundaries and starting points are clearly identifiable.
b)
Boundaries of EAs should not cut across existing Region or District Boundaries. All
social Boundaries should be respected.
c)
EAs should not overlap with one another.
d)
Each EA should be of a reasonable size (in number of household and land area).
Each census library has the geographic extent of a county and is partitioned, or tiled, by the county boundary. The map coordinate system of the Census Library is Universal Transverse Mercator (UTM). All the data are stored in zone 35 to 37. Units are meters. The datum is Arc1960.
Statistical Methods, Standards and Guidelines
114 6.2. Naming Conventions Layer under development should be named to identify their data content and be easily recognized by the user.
Initial and processed coverage names should conform to stand ardized naming conventions recommended by ESRI.
Intermediate coverages that are generated during processing should be named so they are clearly identified as the most current coverage.
The first letter of a file must be an alpha term. It is recommended that coverage names be limited to six to eight characters, and not contain any extensions.
6.3 Data Output Specifications
6.3.1. Development of sets of EAs and SAs
The sets should be in PDF format
Sets should be sized to fit A3 paper
Sets should be presented in a layout as provided in the templates
6.3.2. Printing of EAs and SAs Paper size should be A3 for all EAs and SAs and should be colour printed in two copies each. The paper to be used should be one suitable for map printing; preferably waterpro of paper type.
6.3.3. Map Output
A plotted map must have a textual clause, or disclaimer, which states the original intent of the data,
or warns about the map's usage. It must also include the plot date, the agency which composed the
map, the data sources, and the latest revision of the database.
Other map elements which may be included optionally are:
Scale bar
Symbol key
North arrow
Statistical Methods, Standards and Guidelines
115
National emblem and/or NBS logo
Corner grid tics
Tic coordinates
Note: A LEGEND directory groups together with coverage such as scale bars, north arrows and the
Organization logo are for general use.
National Bureau of Statistics
Director General
P.O. Box 796 Dar es Salaam
Telephone +255 22 2122724
General Office
P.O. Box 796 Dar es Salaam
Telephone +255 22 2122722/3
Fax:
+255 22 2130852
E-mail:
[email protected],
[Website www.nbs.go.tz]
Vision To be a preferable source of official statistics in Tanzania
Mission To facilitate informed decision-making process, through provision of relevant, timely and reliable user-driven statistical information, coordinating statistical activities and promoting the adherence to statistical methodologies and standards