en-1711186765-STATISTICAL METHODS, STANDARDS & GUIDELINES PUBLICATION - FEBRUARY 2012.pdf

Statistical Methods, Standards and Guidelines

81 The survey collects distributive trade statistics using questionnaires designed to obtain basic information from distributive trade outlets. The survey is done on the sample basis covering municipalities, cities, districts headquarters and towns, so only selected wholesale and retail outlets throughout the country are covered. The cla ssification of commodities are based on the International Standard Industrial Classification (ISIC) Revision 3.

The assumption is that, in practice, complete coverage of retail, wholesale is not possible taking into account financial constraints. Also many of the establishments doing business in those kinds of activities operate in a manner that makes it very difficult to find them, even during the time of fi eld work.

The sources of data are wholesale and retail trade outlets selected throughout the coun try. Questionnaires are administered by a team of the trained enumerators with close supervision from NBS offices throughout the Country. The enumerators do the data collection exercise by using the structured questionnaires.

Neither the mailing system nor the uses of telephones are considered practical for data collection in Tanzania. Therefore the collection medium chosen are personal delivery and recovery of documents by a small group of well-trained enumerators who visit all selected Regions.

5.8 AGRICULTURE SAMPLE CENSUS The Agriculture Sample Census is designed to meet the data needs of a wide range of users down to district level including policy makers at local, regional and national levels, rural development agencies, funding institutions, researchers, NGOs, farmer organizations, etc. As a result the dataset is both more numerous in its sample and detailed in its scope compared to surveys. To date , Tanzania Agricultural Census is the most detailed in Africa. The census is normally carried out in order to:

 Identify structural changes if any, in the size of farm household holdings, crop and livestock production, farm input and implement use. It also seeks to determine if there are any improvements in rural infrastructure and the level of agricu lture household living conditions;

Statistical Methods, Standards and Guidelines

82  Provide benchmark data on productivity, production and agricultural practices in relation to policies and interventions promoted by the Ministry of Agriculture and Food Security and others stake holders.

 Establish baseline data for the measurement of the impact of high level objectives of the Agriculture Sector Development Programme (ASDP), National Strategy for Growth and Reduction of Poverty (NSGRP) and other rural development programmes and projects.

 Obtain a benchmark data that will be used to address specific issues such as: food security, rural poverty, gender, agro-processing, marketing, service delivery, etc.

Methodology

1. Census Organisation The Census is conducted by the National Bureau of Statistics (NBS) in collaboration with the sector Ministries of Agriculture, and the Office of the Chief Government Statistician in Zanzibar (OCGS).
   At the National level the Census is headed by the Director General of the National Bureau of Statistics with assistance from the Director of Economic Statistics. The Planning Group oversee the operational aspects of the Census and this consists of staff from the Department of Agriculture Statistics of NBS and representatives of the Department of Policy and Planning of the Ministry of Agriculture and Food Security (MAFS). At the regional level, implementation of census activities is overseen by the Regional Statistical Office of NBS and the Regional Agriculture Supervisor from the Ministry of Agriculture and Food Security. At the District level, the Census activities are managed by two Supervisors from the President‟s Office, Regional Administration and Local Government (PORALG). The supervisors manage the enumerators who also come from PORALG.

2. Tabulation Plan Preparation The tabulation plan is developed following user group workshops and thus reflects the information needs of the end users. It takes into consideration the tabulations from previous censuses and surveys to allow trend analysis and comparisons.

3. Sample Design The Mainland sample consists of 3,221 villages. These villages are drawn from the National Master Sample (NMS) developed by the National Bureau of Statistics (NBS) to serve as a national

Statistical Methods, Standards and Guidelines

83 framework for the conduct of household based surveys in the c ountry. The National Master Sample was developed from the 2002 Population and Housing Census. The total Tanzania Mainland sample is 48,315 agricultural households. In Tanzania Zanzibar, a total of 317 EAs are selected and 4,755 agriculture households are covered. Nationwide, all regions and districts are sampled except three urban districts (two from Mainland and one from Zanzibar).

4. Questionnaire Design and Other Census Instruments The questionnaires are designed following user meetings to ensure t hat the questions asked are in line with users data needs. Several features are incorporated into the design of the questionnaires to increase the accuracy of the data:

 Where feasible all variables are extensively coded to reduce post enumeration coding error.

 The definitions for each section are printed on the opposite page so that the enumerator could easily refer to the instructions whilst interviewing the farmer.

 The responses to all questions are placed in boxes printed on the questionnaire, with one box per character. This feature makes it possible to use scanning and Intelligent Character Recognition (ICR) technologies for data entry.

 Skip patterns are used to reduce unnecessary and incorrect coding of sections which do not apply to the respondent.

 Each section is clearly numbered, which facilitated the use of skip patterns and provide a reference for data type coding for the programming of CSPro, SPSS and the dissemination applications.

Three other instruments are used:  Village Listing Forms are used for listing households in the village and from this list a systematic sample of 15 agricultural households are selected.

 A Training Manual which is used by the trainers for the cascade/pyramid training of supervisors and enumerators

Statistical Methods, Standards and Guidelines

84  Enumerator Instruction Manual which is used as reference material.

5. Field Pre-testing of the Census Instruments The Questionnaire should be pre-tested in areas where different characteristics of farming and livestock keepers are found. This is conducted in orde r to test the wording, flow and relevance of the questions and to finalise crop lists, questionnaire coding and manuals. In addition to this, several data collection methodologies are to be finalised, namely, livestock numbers in pastoralist communities, cut flower production, mixed cropping, use of percentages in the questionnaire and finalising skip patterns and documenting consistency checks.

6. Training of Trainers, Supervisors and Enumerators During training, cascade/pyramid training techniques are employed to maintain statistical standards. The top level of training is provided to national and regional supervisors. The trainers are members of the Planning Group from the National Bureau of Statistics and the sector Ministries of Agriculture. In each region, three training sessions are conducted for the district supervisors and enumerators. In addition to training them in field level Census methodology and definitions, emphasis is placed on training the enumerators and supervisors in consistency ch ecking. Tests are given to the supervisors and enumerators and the best 50 percent of the trainees are selected for the enumeration of the smallholder questionnaire and the community level questionnaire. The household listing exercise is carried out by all trained enumerators.

7. Information, Education and Communication (IEC) Campaign Radios, television s, newspapers, leaflets, t -shirts and caps are used to publicize the Agriculture Sample Census. This help s in sensitizing the public for the field level activities. The t -shirts and caps are given to the field staff and the village chairpersons. The village chairpersons help to locate the selected households.

8. Data Collection The data collection methods used during the census is by interview and no p hysical measurements, e.g., crop cutting and field area measurement is taken. Field work is monitored by a hierarchical system of supervisors at the top of which is the Mobile Response Team followed by the Regional Supervisors and District Supervisors. The Mobile Response Team consists of Principal Supervisors who provide overall direction to the field operations and responded to queries arising outside the

Statistical Methods, Standards and Guidelines

85 scope of the training exercise. The mobile response team consist s of the Manager of Agriculture Statistics Department, the Desk Officer for the Census and senior officers. Decisions made on definitions and procedures are then communicated back to all enumerators via the Regional and District Supervisors.

9. Field Supervision and Consistency Checks Enumerators are trained to probe the respondents until they are satisfied with the response given before they record them in the questionnaire. The first check of the questionnaires is done by enumerators in the field during enumeration. The second check is done by the district supervisors followed by Regional and National Supervisors. Supervisory visits at all levels of supervision focus on consistency checking of the questionnaires. Inconsistencies encountered are corrected, and where necessary call backs are made by the enumerator to obtain the correct information. Further quality control checks are made through a major post enumeration checking exercise where all questionnaires are checked for consistencies by supervisors in the district offices.

10. Data Processing and Analysis Data processing consists the following processes:  Data entry  Data structure formatting  Batch validation  Tabulation

11. Data Entry Scanning and ICR data capture technology for the small holder questionnaire are used. This not only increase s the speed of data entry, it also increase s the accuracy due to the reduction of keystroke errors. Interactive validation routines are incorporated into the ICR software to trap errors during the verification process.

Prior to scanning, all q uestionnaires undergo a manual cleaning exercise. This involve s checking that the questionnaires have a full set of pages, correct identification and good handwriting.

CSPro is used for data entry of all Large Scale Farm and Community based questionnai res due to the relatively small number of questionnaires. It is also used to enter small holder questionnaires that are rejected by the ICR extraction application.

Statistical Methods, Standards and Guidelines

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12. Data Structure Formatting A program is developed in visual basic to automatically alt er the structure of the output from the scanning or extraction process in order to harmonise it with the manually entered data. The programmes automatically checks and change the number of digits for each variable, the record type code, the number of que stionnaires in the village, the consistency of the Village ID Code and saves the data of one village in a file named after the village code.

13. Batch Validation
    A batch validation program is developed in CSPro in order to identify inconsistencies withi n a questionnaire. This is in addition to the interactive validation during the ICR extraction process.
    The procedure varies from simple range checking within each variable to more complexes checking between variables. After the long process of data clea ning, the tabulations are prepared based on a pre-designed tabulation plan.

14. Tabulations
    Statistical Package for Social Sciences (SPSS) is used to produce the Census tabulations and Microsoft Excel is used to organize the tables and compute additional indicators. Excel is also used to produce charts while ArcView and Freehand are used for the maps.

15. Analysis and Report Preparation The analysis in the reports focuses on regional comparisons, time series and national production estimates. Microsoft Excel is used to produce charts; ArcView and Freehand are used for maps, whereas Microsoft Word is used to compile the report.

16. Data Quality A great deal of emphasis is placed on data quality throughout the whole exercise from planning, questionnaire design, training, supervision, data entry, validation and cleaning/editing. As a result of this, it is believed that the census is highly accurate and representative of what is experienced at field level during the Census year. With very few exceptions, the variables in the questionnaire are within the norms for Tanzania and they follow expected time series trends when compared to historical data.

Large Scale Farms

Statistical Methods, Standards and Guidelines

87 The survey covers all Large Scale Farms in Tanzania Mainland. There is a total of 96 8 Large Scale Farms in Tanzania Mainland. Methodology The designed questionnaires that are used in the Agriculture Sample Census have been reviewed based on the census results and are posted to the Regional Statistical Managers who collect the data from all the 968 large scale farms. The reference period is the agriculture year. An agriculture year in Tanzania commences on 1 st October and ends on 30 th of September of the following year. A list of large scale farms is updated annually by the Regional Statist ical Managers. The questionnaires are edited by the Regional Statistical Managers before they are posted to NBS headquarters, Dar es Salaam for data entry and analysis.

Data entry The data is being entered manually using CSPro. Data cleaning is done by th e subject matter specialist and programmer.

Tabulation Table format is being given to the programmer who produces the tables for analysis.

Analysis Analysis takes place in the Department of Agriculture.

Routine Data Quarterly agricultural production and producer unit prices are normally collected by the Extension Officers from the Villages.

Methodology The data is collected at the village level by the extension officers who estimate production of various crops grown in the respective villages. They then send the data to the Districts who compile them to give District estimates of production and producer unit price of each crop. The Regional Statistical Managers collect the returns and send the data to the NBS head office.

Data Entry The Regional Statistical Managers enter the data in the e-excel spread sheet and send them to the NBS head office.

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88

Data Cleaning The Regional Statistical Managers check the data for consistency before entering them in the spread sheet.

Analysis The Department of Agriculture does not produce any report on the data collected but compiles them to give Regional Production and unit price of each crop and submit to the National Accounts Department for the calculation of GDP.

5.9 GROSS DOMESTIC PRODUCT (GDP)

5.9.1 ANNUAL GROSS DOMESTIC PRODUCT Gross Domestic Product (GDP) is the sum of values added of all domestic producers in the economy. It represents the money value of all goods and services produced within a country out of economic activity during a specified period usually a year, before the provision of the consumption of fixed capital.

The basic formula for calculating the GDP is: Y= C+ I + E + G Where Y = GDP
C = Consumer Spending I = Investment made by Industry E = Excess of Export over Imports (X – M) G = Government Spending

Objectives of the Gross Domestic Products are

1. To measure the performance of each economic activity in the country.
2. To measure the contribution of each economic activity in the economy.
3. To compare economic performance among different economic territories.