Statistical Methods, Standards and Guidelines 59
Data Processing Data processing starts concurrently with the fieldwork. The data processing personnel includes supervisors and a questionnaire administrator, who ensures that the expected numbers of questionnaires from all clusters are received. The CSPro computer package is used for data entry.
4.5
POPULATIONS AND HOUSING CENSUS (PHC)
The United Nations defines a population census as the total process of collecting, compiling,
evaluating, analyzing and publishing or otherwise disseminating demographic, economic and
social data pertaining, at a specified time, to all persons in a country or in a well delineated part of
a country.
In other words, a population census is the complete count of all persons in a country at a given time. It is the primary source of detailed data on the size, distribution and composition of population. It covers all population groups e.g. private households, institutions, homeless, and migratory populations, for all geographic and/or administrative units in the country. The United Nations recommend that countries should conduct at least one population census every 10 years.
4.5.1 The objective and uses of the Population Census
The fundamental objective of conducting Census is to provide the government with information
on the size, distribution, composition and other social economic characteristics of the population
as well as information on housing conditions. This information is important in providing updated
benchmark data for formulation, implementation, monitoring and evaluation of population
programmes and policies. The up-to-date information supports, among other things, the evaluation
of the implementation of the Tanzania Development Vision 2025, Vision 2020 for Zanzibar as
well as health, social and economic reforms in a de-centralized government framework.
Specific objectives of the census include:
(i)
Increasing availability and accessibility of accurate, timely and reliable data on
demographic and socio-economic characteristics for policy formulation,
monitoring and evaluation of development programmes;
(ii)
Increasing knowledge of stakeholders on socio-economic and demographic
characteristics of Tanzania population as well as patterns and trends of growth;
(iii)
Increasing utilization of socio-economic and demographic data for designing,
monitoring and evaluating development programmes; and
Statistical Methods, Standards and Guidelines 60
(iv) Strengthening capacity of the National Bureau of Statistics (NBS) and Office of Chief Government Statistician (OCGS) in carrying out population and housing censuses particularly in the areas of planning, collecting, processing, analysing, disseminating and utilizing census and other data.
Use of Population Census The population and housing census’ data is an important input for the preparation of economic and development policies, monitoring the improvement in the quality of life of the population, as well as developing a system of sustainable development in general.
4.5.2 Methodology of data production
Census Budget The cost of Census exercise is covered by the Government and development partners.
Census Cartographic Work The main census–related objective of cartographic work is to delineate the entire country into Enumeration Areas (EAs) in order to produce maps required for census operations. The most important principle followed in delineating an EA is to ensure that no EA can cut across the existing administrative boundaries of regions, districts, wards/shehia or villages /mitaa.
The 2012 census cartographic work fully embraced the technological advancements in Geographical Information System (GIS) development. In particular, the census cartography used satellite imagery and aerial photography. Delineation of EA boundaries was done using a Global Positioning Systems (GPS). In addition, coordinates of prominent features existing in each particular EA were also picked and recorded.
Pilot Census A pilot census is conducted to assess the whole process of census and Post Enumeration Survey (PES) operation. The pilot census determines the workload of enumeration, logistic support, enumeration procedures, data processing and acceptability by the public in general. Administrative control and management issues are also tested through the pilot census.
Staff Recruitment and Training of Field Staff Recruitment and training of enumerators during enumeration is given a special attention as large number of staff is required. Traditionally, primary school teachers have been involved as
Statistical Methods, Standards and Guidelines 61
enumerators/supervisors. Supervisors and enumerators are trained at regional level. However, for the 2012 Population and Housing Census, other staff from different government sectors were also involved as enumerators and supervisors. The District Census Committee recruited these staff during enumeration exercise.
Questionnaires Two main types of questionnaires used in PHC are the Long and Short questionnaires. Other questionnaires that are used include questionnaire for special population groups, questionnaire for diplomats, questionnaire for hotels or lodges, hospitals and travelers as well as a community questionnaire that covers all social amenities, land use pattern and environmental or natural features (e.g. water sources, forest or vegetation cover).
The main topics included in the census questionnaires are demographic characteristics (Relationship, Sex, Age, Disability, Marital Status, Citizenship and Place of Residence); Literacy and Education; Migration; Economic Activity; Fertility; General and Maternal Mortality; Social Security Funds; Tanzanians Living Abroad (Diaspora); Agriculture; Ownership of Assets and Housing Conditions. The 2012 PHC questionnaires were paper-based.
Census Enumeration Census enumeration is an important operation which determines the success or failure of a census. Quality of census depends on how the exercise is conducted. Enumeration involves house-to- house visit by trained numerators using structured questionnaire with the objective of enumerating all persons in the country.
Data Processing Data processing exercise is done through scanning technology and computers for manual data entry for questionnaires that for some reasons will be rejected by scanner. The processing of the 2012 PHC data were captured from the questionnaires electronically using the Optical Mark Reader (OMR) scanning technology, and through manual data entry for special questionnaires such as community questionnaires. Data processing started with validation of the EAs, followed by sorting and separation of the questionnaires.
Statistical Methods, Standards and Guidelines 62
Data Analysis and Dissemination Data analysis and dissemination is undertaken after completion of data cleaning and data processing. The analysis is undertaken by teams of experts from Government Ministries, Research Institutions and Higher Learning and Training Institutions. A number of experts from within and outside the country provide technical assistance.
Report Writing Preliminary report is prepared by professionals from NBS and OCGS staff and the main report is prepared by professionals from NBS, OCGS and other ministries.
4.6
EDUCATION AND HEALTH STATISTICS
4.6.1 The objective and uses of Education and Health Statistics:
The health and education statistics are inputs to the Economic Survey Report, which is produced
annually by the Ministry of Finance and Planning.
4.6.2 Methodology of data production
Method of Data Collection The education data from Higher Learning Institutions are collected using paper questionnaires. These questionnaires are sent to the Regional Statistical Offices (RSMs) for distribution to the Higher Learning and Training Institutions existing in each region. These questionnaires are filled- in by a responsible person in the respective institution under the supervision of the Regional Statistical Managers (RSM) and headquarter supervisor for quality assurance. On the other hand, education data from pre-primary, primary, secondary, teacher education, adult and non-formal education, technical and vocational educations are obtained from Ministry of Education and Vocational Training.
Education
The education data and information collected and compiled includes:
(i)
The yearly total enrolment according by sex and/or courses,
(ii)
The total number of teachers in a given year,
(iii)
The total number of students, and
(iv)
The number of lecturers in all higher learning institutions.
Statistical Methods, Standards and Guidelines 63
Health
Health Statistics are collected from the Ministry of Health, Community Development, Gender,
Elderly and Children by staff from the Department of Social and Demographic Statistics.
The health data and information that is collected and compiled includes:
(i)
The number of health professionals,
(ii)
Ownership of health facilities,
(iii)
The total health facilities according to ownership (Private, Government,
Government agencies and Religious Health Facilities),
(iv)
The number of patients attended by different health facilities annually.
These statistics are usually updated every year to facilitate the production of the Economic Survey Report produced annually. As such, these data are collected from the second week of January and submitted to the National Accounts Department at NBS in March for further compilation and submission to the Ministry of Finance and Planning. They are expected to reach the Ministry of Finance not later than mid-April every year.
4.7
HOUSEHOLD BUDGET SURVEY (HBS)
Household Budget Surveys are intended to collect, compile and analyze numerical information on
household consumption, expenditure and income. Based on this information it is possible to assess
the impact of various policies on people and consequently identify the most vulnerable groups of
the population.
4.7.1 The objective and uses of HBS The main aim of the HBS is to get information from private households on socio-economic activities, household consumption, income and expenditure, housing characteristics as well as ownership of assets.
Use of HBS The HBS is a useful source of information to planners and policy makers, non-government organizations, academicians and other stakeholders, including regional and international
Statistical Methods, Standards and Guidelines 64
organizations. The survey findings also facilitate formulation of policies, planning and evidence based decision-making within the government and the business community and stimulate further research and in-depth analyses.
4.7.2 Methodology of data production
Sample design
The sample design for the HBS is usually done in two stages and is intended to provide estimates
at the National level (Tanzania Mainland), Dar es Salaam, Other Urban Areas and Rural Areas.
The first stage involves selecting sample points (clusters), consisting of enumeration areas (EAs)
delineated from the Tanzania Population and Housing Census (PHC). The selection of the sample
EAs is based on their probabilities proportional to their sizes (PPS) within each stratum.
Following the selection of the sample EAs at the first sampling stage, a complete households
listing is carried out in each of the selected EA. At the second sampling stage households are
systematically selected from the listed households from each EA.
Survey Instruments Just like other surveys/censuses, the HBS data are collected through questionnaires. The survey questionnaires are designed to fulfill the main objectives of the survey. During the recent (2011/12) HBS, apart from the listing form, there were five types of questionnaires/forms. Household questionnaires Form I to Form V were used during the main survey; Form I was used to collect socio-economic and demographic information of household members. It has sections on demographic information, immigration, education, health, disability, and time use. Data on non- food consumption were recorded in Form II. It contains sections on dwelling, utilities, water, sanitation and household expenditure. Form III collected data on the labour status of household members, household businesses and individual income. Form IV was concerned with land; agriculture, crops and livestock. Form V which is also known as household diary was used to record daily transactions on consumption and expenditure of the household.
On the other hand, there was an instruction manual explaining all survey details and questionnaire contents. An attempt was made to give explanation on each question existed in the questionnaires. Also codes for various items or transactions that were anticipated to be found in households were provided in this document. Each enumerator and supervisor was provided with this manual for reference each time they undertake the filling-in or reviewing the already filled-in questionnaires.
Statistical Methods, Standards and Guidelines 65
Training Training is usually in two phases; the first one is the training of trainers (TOT) where all anticipated trainers gather and discuss the details of the training, the methods of training and the training schedule. The second phase of the training is the Training of Enumerators and Supervisors. Due to a large number of enumerators and supervisors that are usually involved in the HBS, the training of enumerators and supervisors is conducted in zones to ensure that all participants are properly trained. The training is consisted of classroom lectures, mock interviews and field practices which involve interviewing households in both rural and urban areas.
Data Collection
Each enumerator is assigned a cluster for the whole year. Before beginning of enumeration, each
enumerator is provided with the necessary information in hard copies to deliver to the local
leaders and a letter of introduction to every selected household. Up to the recent HBS, each
enumerator has been interviewing two household for either 28 or all days in the respective
calendar month. The two households of each month may have different days of starting interviews
depending on the decisions made by the technical teams for a number of reasons. Details of these
variations are usually an important part of the survey report so as to assist users of the statistics
understand methods used during the entire process of the survey.
Quality Control during Fieldwork
As part of the entire process of HBS data collection, a quality control team is usually formed. The
team ensures that the data being collected meet expected quality and standards. The team is
mainly composed of NBS staff from the head office and the HBS Quality Assurance Consultant
when necessary.
Processing Editing of filled-in questionnaires is a two stages exercise. The primary editing is done at the respective regional statistical office. This ensures that all problems that require going back to the specific household are solved before the questionnaires are sent to the main office where it may take time to rectify the problems. The second stage is at the main office where the editing is conducted in two ways, namely the manual editing and computer editing. The manual phase involves manual editing of the questionnaires. This starts as soon as the first bunches of completed questionnaires are received at the headquarters. Computer editing is for data that have been entered, consistence checks are run to detect any inconsistencies and mistakes either committed in