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The statistics Act Cap 351 section 18 - 20 and section 31 explains about the terms of which statistics are collected, processed and disseminated. The Bureau takes all necessary steps to ensure confidentiality of the official statistics.
1.2.2 Internal governmental access to statistics prior to their release is publicly identified
• The public is made aware of internal government access to statistics prior to their release to the public
The CPI is not released to any governmental organization prior to dissemination. The CPI, when completed is disseminated same day and time to all users.
1.2.3 Products of statistical agencies/units are clearly identified as such.
• Statistical products are clearly identified so that the public is aware of what the data producing agency takes responsibility for.
CPI publication are clearly stated by name and logo of NBS, there is no joint publication of CPI.
1.2.4 Advance notice is given of major changes in methodology, source data, and statistical techniques. • Users of statistics are made aware in advance of major changes in methodology, source data, and statistical techniques.
Data users are normally well informed in advance about changes in methodologies, data sources and statistical techniques through Metadata reports and these are shared with users on the NBS website and during workshops or dissemination workshops of the CPI.
1.3 Ethical standards
1.3.1 Guidelines for staff behavior are in place and are well known to the staff.
• A clear set of ethical standards has been prepared
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NBS has a staff regulation and codes of Ethics and conducts that guides management and staff on ethical standards of the office. Therefore, all NBS staff are issued with a copy of the service rule to inform them of ethical standards and each member of staff signs oath of secrecy.
• Staff are made aware of the ethical standards.
NBS staff are made aware of the guiding rules and ethical standards provided under the Code of Ethics for Public Servants and they are periodically reminded during all staff meetings and Workers Council meetings. Newly recruited staff are provided with induction course in order to understand public servants ethics. Management and discipline committee also assures ethical standards are observed by staff.
- Methodological soundness
2.1 Concepts and definitions
2.1.1 The overall structure in terms of concepts and definitions follows internationally accepted standards, guidelines, or good practices
• CPI concepts and definitions are based on international standards and recommendations, and good practices
CPI adhere to the guidelines outlined in the EAC guidelines for compiling consumer price indices (HCPI) and Consumer Price Index (CPI) Manual, Concepts and Methods 2020 when compiling the Consumer Price Index (CPI). National Bureau of Statistics (NBS) has developed guidelines for concepts and definitions for official statistics that are in line with the CPI manual, serving as a methodological reference for producing CPI statistics.
• Expenditure estimates are compiled at a sufficient level of commodity and service detail
Level of detail for commodities and services; and household residential capital formation expenditures for the analysis of price movement uses the Classification of Individual Consumption by Purpose (COICOP) 2018. The CPI uses to classify household consumption and expenditure.
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Basically, the data are collected through Household Budget Survey (HBS) where it used the COICOP at the elementary level. Expenditure estimates from HBS and other sources are developed at an item level.
2.2 Scope
2.2.1 The scope is broadly consistent with internationally accepted standards, guidelines, or good practices
• The institutional unit and transaction scope of the CPI comprises a selection of aggregates fitting within household final consumption and capital formation expenditure as defined in the 2008 SNA.
The consumption expenditures of both urban and rural households regardless of their sizes (number of persons), formality of their economic activities and type of economic activities (farming and non-farming) were included in the Household Budget Survey (HBS) and hence in development of final household expenditures. The expenditure data from the HBS helps to determine the weights of the basket of goods and services.
The CPI's scope involves selecting components that align with the final consumption expenditure as outlined in the EAC guidelines.
• Differences in the scope of coverage between the CPI and the consumption and capital formation final expenditure of the household sector as defined in the 2008 SNA are clearly determined.
The inclusion and exclusion criteria of the item in the CPI final consumption expenditure aggregate is aligned with the international standards as per 2008 SNA. The sales of illegal market goods and services to willing buyers is excluded as per EAC guidelines requirements.
2.3 Classification/sectorization
2.3.1 Classification and sectorization systems used are broadly consistent with internationally accepted standards, guidelines, or good practices.
• The classification and sectorization used in the compilation of the CPI is in broad conformity with internationally accepted systems.
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The CPI uses the Individual Consumption by Purpose (COICOP - 2018) classification to categorize consumption and expenditure and also it adheres to the 2008 SNA for classifying institutional units and transactions, nor does it follow CPC/CPA for product classification. These are the Internationally accepted standards of Classification.
2.4 Basis for recording
2.4.1 Market prices are used to value flows and stocks.
• The valuation rules used for recording flows and stocks are in accordance with the 2008 SNA.
The rules of valuation used to record expenditures for CPI weights are in accordance with 2008 SNA. The computation of CPI weights from HBS uses final household consumption expenditure paid by households involving trade and transportation margins and applicable taxes less subsidies on products. HBS as the main source in computing the consumption expenditure that include valued at purchasers’ prices and value of residential capital acquisitions. The CPI data collection form includes the product specifications comprises of price-determining characteristics of the item, the terms of the transactions, and services provided by the outlet. Any expenditure with discriminatory discounts are excluded. In case of deviations from the concepts earmarked above are kept under review over time to assess their viability.
2.4.2 Recording is done on an accrual basis.
• The timing rules used for recording flows are in accordance with the 2008 SNA.
Prices of goods and services are recorded as they are in the period they are purchased or posted as outlined under the 2008 SNA.
2.4.3 Grossing/netting procedures are broadly consistent with internationally accepted standards, guidelines, or good practices. • The grossing/netting procedures are in accordance with the 2008 SNA. The grossing/netting procedures complied with 2008 SNA and EAC guidelines.
- Accuracy and Reliability
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3.1 Source data
3.1.1 Source data are obtained from comprehensive data collection programs that take into account country-specific conditions.
• The data collection programs employed to compile the consumer price statistics are adequate.
Data collection is conducted at regional level where a list of data sources/outlets is developed during rebasing exercise and periodically reviewed to ensure data collection program is executed as required in the guidelines. Outlets for data collection are broadly sufficient to compile the consumer price statistics whereby the random sampling is used for selecting hospitals , schools and petrol station, supermarkets and purposive sampling is used for selecting data sources such as open markets, fixed-place street vendors, permanent shops such as neighborhood shops, specialized shops etc. Sometimes data are acquired from other government agencies such as EWURA for validating data collected from the outlets. • Household expenditure statistics are collected through a regular household budget survey program for compiling CPI expenditure weights
The NCPI weights are based on monetary expenditures relating to consumption of all households in 26 regions of Tanzania Mainland. The index weights are based on expenditures of both urban and rural households derived from 2017/18 Household Budget Survey. HBS is a multi-stage sample survey derived from the recent population and housing sampling frame with known probability of each selected household. It therefore produces reliable and comprehensive estimates for CPI scope. Data collection for HBS covers twelve months to cater for seasonality nature of household expenditure and includes all residents and non-residents residing in private households, Institutional households such as hospitals and schools are excluded in Tanzania Mainland. HBS Survey questionnaires are constructed involving all key stakeholders and adopts the principles stipulated in EAC guidelines for compilation of poverty indicators. HBS questionnaires are subject to field/pilot testing and observation studies are conducted during the design of survey questionnaires, all these are reviewed periodically to take account of changed circumstances, and proposed changes are pre-
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tested to ensure effectiveness. • A regular representative price survey is conducted to collect consumer prices.
Prices for the goods and services used to calculate the CPI are collected
from vendors and suppliers of goods and services from about 7,000 retail
outlets and service establishments. The CPI basket comprises of 383
goods and services, of which 132 are Food and Non-Alcoholic Beverages
and 251 are Non-Food items. With regard to geographical coverage, the
CPI uses price data collected from all 26 regional headquarters in
Tanzania Mainland.
A combination of scientific and purposive sampling procedures are used
to select outlets and product varieties. Outlets for data collection are
broadly sufficient to compile the consumer price statistics whereby the
random sampling is used for selecting hospitals, schools, petrol station
and supermarkets. Purposive sampling is used for selecting data sources
such as open markets, fixed-place street vendors, permanent shops such
as neighborhood shops, specialized shops etc whereas item/product
varieties commonly consumed are also selected using purposive
sampling. Furthermore, data are acquired from other government
agencies such as EWURA for validating data collected from the outlets.
• The survey is of matched model pricing
Compilation of CPI is based on a fixed basket of goods and services
whereas each product or service contains detailed description of product
specifications (Brand, Weight, Content, etc.) making it possible to collect
prices of the same items overtime reflecting the pure price change. In
event of outlet replacement, a new outlet with similar characteristics with
the old outlet in terms of location and lines of items is purposively
selected to replace the old outlet.
• The
compilation
framework
supports
supplementary
collection.
New products are introduced during the rebasing period, in event of new product emerging in the market and replacing the old item in CPI survey sample, regional statisticians purposively select a new item similar to the old item to update the survey sample to reflect the current pattern. CPI data collection is conducted on monthly basis, though data collection
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for some items e.g electricity and water bills is done on quarterly basis. However a separate data collection framework is planned to be implemented in the future for collecting price data for rents and other items with high price volatility. • The data collection programs are sufficiently open and allow for versatility to new developments in sources.
Stakeholders are involved in identifying new product/market developments that the CPI compilation system needs to take into account during the rebasing period. The EAC Guideline is adhered to compilation of CPI including any changes that need to be taken into account in the consumer price index compilation system.
3.1.2 Source data reasonably approximate the definitions, scope, sectorization, classifications, valuation, and time of recording required.
• Source data approximate the definitions, scope, classifications, valuation, and time of recording required in the CPI
The source data are consistent with the definitions, scope and
classifications, and the time of recording and valuation of CPI estimates.
The frequency of the price collection survey is adequate to support the
publication frequency of the index.
Selection of data source is based on statistical procedures and prices are
collected monthly at specific period of time from all outlets.
3.1.3 Source data are timely.
• Source data and detailed data from other statistical systems are obtained on timely
Every month, a specified time window is set aside for price collection whereas NBS usually collects CPI price data from all outlets before 14th day of the particular reference month. Consumer price statistics are disseminated on the 8th of the subsequent month after the surveys reference month.
3.2 Assessment of source data
3.2.1 Source data—including censuses, sample surveys, and administrative records—are routinely assessed, e.g., for coverage, sample error,