The 2012-2013 Tanzania National Panel Survey (NPS) is the third round in a series of nationally representative household panel surveys that collect information on a wide range of topics including agricultural production, non-farm income generating activities, consumption expenditures, and a wealth of other socio-economic characteristics. All three rounds of the NPS have been implemented by the Tanzania National Bureau of Statistics (NBS). The first round of the survey was conducted over twelve months, from October 2008 to September 2009. The main fieldwork of the second round of the NPS started in October 2010 and finished in September 2011, with specialized tracking teams remaining in the field until November 2011. Similarly, the duration and timing of the field work for the third round of NPS was from October 2012 to November 2013.
The main objective of the NPS is to provide high-quality household-level data to the Tanzanian government and other stakeholders for monitoring poverty dynamics, tracking the progress of the MKUKUTA II poverty reduction strategy 1, and to evaluate the impact of other major, national level government policy initiatives. As an integrated survey covering a number of different socioeconomic factors, it compliments other more narrowly focused survey efforts, such as the Demographic and Health Survey on health, the Integrated Labour Force Survey on labour markets, the Household Budget Survey on expenditure, and the National Sample Census of Agriculture. Secondly, as a panel household survey in which the same households are revisited over time, the NPS allows for the study of poverty and welfare transitions and the determinants of living standard changes.
Kind of Data
Sample survey data [ssd]
Unit of Analysis
The 2012-13 NPS covers the following topics:
- Household identification
- Survey staff details
- Household member roster
- Food outside the household
- Subject welfare
- Food security
- Water and sanitation
- Consumption of food over the past one week
- Non-food expenditures (past one week & one month)
- Non-food expenditures (past twelve months)
- Household assets; Family/household non-farm enterprises
- Assistance and groups
- Credit; Finance
- Recent shocks to household welfare
- Deaths in the household
- Household recontact information
- Filter questions; Anthropometry.
- Household roster
- Plot roster
- Plot details
- Crops by plot
- Household totals ( production and sales)
- Permanent crops by plot
- Permanent crops
- Household totals (production and sales)
- Input vouchers
- Out grower schemes and contract farming
- Processed agricultural products and agricultural by-products
- Farm implements and machinery extension
LIVESTOCK AND FISHERY
- Household member roster
- Livestock stock
- Animal health
- Animal power & dung
- Other livestock products
- Household labour
o Hired labour
- Community identification
- Survey staff details
- Access to basic services
- Investments projects
- Land use
- land & livestock
- Market prices Local units.
Agriculture & Rural Development
Land (policy, resource management)
The survey covers all individuals included in the households in the sample. The eligibility requirement for the NPS is defined as any household member aged 15 years and above, excluding live-in servants. Households with at least one eligible member where completely interviewed, including any subsequent non-eligible members present in the household. Any household or eligible members that had either moved or split away from a primary household were tracked and interviewed in their new location.
Producers and sponsors
National Bureau of Statistics
Ministry of Finance,Tanzania
Ministry of Agriculture, Food Security and Cooperatives
Government of Tanzania
Ministry of Finance
Government of Tanzania
Millennium Challenge Account-Tanzania
Government of Tanzania
United Nations Fund of Development Program
The original sample size of 3,265 households for the 2008/2009 survey was designed to be representative at the national, urban/rural, and major agro-ecological zones. The total sample size of 3,265 households is clustered in 409 Enumeration Areas (2,063 households in rural areas and 1,202 urban areas) across Tanzania and Zanzibar. The NPS sample allows analysis at 4 primary domains of inference, namely: Dar es Salaam, other urban areas on mainland Tanzania, rural mainland Tanzania, and Zanzibar. The NPS 2012/2013 revisits all households interviewed during the first two waves; NPS 2008/2009 and NPS 2010/2011. This includes the originally sampled 3,265 households plus split-off households added into the sample in the second round of the NPS. Thus, the total sample at the onset of the NPS 2012/2013 consisted of 3,924 target households. The eligibility requirement for the NPS is defined as any household member aged 15 years and above, excluding live-in servants. Households with at least one eligible member where completely interviewed, including any subsequent non-eligible members present in the household. Any household or eligible members that had either moved or split away from a primary household were tracked and interviewed in their new location. It is important to note that the NPS 2012/2013 sample includes individuals meeting the eligibility requirement that were interviewed as part of the NPS 2008/2009 wave but were not located and interviewed during the NPS 2010/2011. This constituted an additional 703 individuals assigned to their last know associated household.
To identify these individuals in the NPS 2012/2013 sample household rosters they received an ID code in the range of 101-130; the ID code was formed by the addition of 100 to their NPS 2008/2009 roster ID. The resulting sample size for the third round of NPS, including NPS 2008/2009 and NPS 2010/2011 households plus new, or split-off, households in NPS 2012/2013, is 5,015 households. For a more detailed description of the original sample design, please reference the NPS 2008/2009 Basic Information Document.
Deviations from the Sample Design
Panel Attrition As with most panel surveys a certain portion of panel respondents are not able to be reinterviewed over time. This attrition of panel respondents can lead to attrition bias where respondents drop out of the survey non-randomly and where the attrition is correlated with variables of interest. The NPS has fortunately maintained low attrition over the waves, thus minimizing the potential for attrition bias within the datasets. The target sample of eligible households for the NPS 2012/2013 was 3,924, representing original NPS 2008/2009 households plus new or split-off households added to the NPS in the second round. Of these households 3,786 households were re-located and re-interviewed. This translates to a household attrition rate of roughly 3.50 percent between the NPS 2010/2011 and NPS 2012/2013. At the individual level, 12,280 of the 13,278 eligible household members where reinterviewed during the NPS 2012/2013, equating to an individual attrition rate of roughly 7.52 percent between the NPS 2010/2011 and the NPS 2012/2013. Total household attrition for the NPS, up to round three, is 4.84 percent.
Approximately 95 percent
In order to produce nationally representative statistics with the NPS data, it is necessary to apply weighting or expansion factors. The panel survey weights adjust for differences in the probability of selection into the NPS 2008/2009 sample for observations in various strata, 2008/2009 households splitting into multiple households in 2010/2011 and splitting even further in 2012/2013, and attrition between rounds of the survey. The first round of the NPS sample was a multi-stage clustered sample design. First stage sampling involved the selection of survey clusters with the probability of selection proportional to cluster size within a stratum. The sampling of these clusters was stratified along two dimensions:
(i) eight administrative zones (seven on Mainland Tanzania plus Zanzibar as an eighth zone), and
(ii) rural versus urban clusters within each administrative zone.
The combination of these two dimensions yields 16 strata. In rural areas a cluster is defined as an entire village. In urban areas a cluster is defined as a census enumeration area. As a general rule, the probability of selection was higher for clusters within strata where existing data sources showed that the variance of key variables of interest for the NPS (e.g. household consumption and maize production) were likely to be very high - implying the need for more observations to produce reliable estimates.
The expansion factors for the NPS 2012/2013, variable “y3_weight”, have been integrated into Section A, “HH_SEC_A” of the household dataset. Additionally, unique identifiers for the first stage sampling units, “clusterid”, and for the sampling strata, “strataid” can also be located in Section A of the household dataset. The methodology used to calculate the panel weights for the NPS 2012/2013 was developed as part of the LSMS-ISA work program.
Dates of Data Collection
Data Collection Mode
Computer Assisted Personal Interview [capi]
Data Processing & Management:
The NPS 2012/2013 contains a robust multi-level quality assurance and data management system. Great effort was placed on the development and utilization of this system by the NBS with technical assistance form the World Bank prior to the implementation of the NPS 2012/2013 to assist in the management of the complex household panel survey and address the growing need for high quality timely data. The NPS utilizes a concurrent field entry system known a CAFE; Computer Assisted Field Entry. This system was selected to increase the availability of data for review by managing staff as well as to provide regular and consistent quality assessment of data directly to the field staff. As with the earlier rounds, CSPro was used for data entry and initial quality reporting while STATA was utilized to perform complex aggregated checks.
Building off the work conducted for the NPS 2010/2011, the NPS 2012/2013 data entry application further develops the quantity and complexity of data quality checking routines while simplifying reporting. Furthermore, due to the panel nature of the survey, where applicable and appropriate, data was checked against previous round data. As data entry took place while in the interview area, when data issues were identified and reported, field teams would return to households and clarify and correct inconsistent information prior to the transmission of the data to headquarters. Data files from completed clusters were transmitted to NBS headquarters using 3G USB modems. Received data files were concatenated at the headquarters, and regular checks were performed to ensure the fieldwork was proceeding according to the schedule and that quality standards were met. During the course of field work data was routinely checked at the aggregate level to identify any potential issues and where identified additional checks where integrated into the CAFE system.
Estimates of Sampling Error
Further adjustment of the data post-entry was conducted under the principle of absolute certainty where adjustments must be evidence based and correction values true beyond a reasonable doubt. As such, the resulting final datasets may still contain some inconsistencies and outliers. Handling of these values is thus left entirely to the data user. Throughout the data processing system versions of the data are archived at all key steps and all checking and cleaning syntax documented and archived.
Throughout the course of field work, the field teams regularly sent the paper questionnaires back to the NBS headquarters for further processing. Once the paper questionnaires and data files for completed EAs were received at NBS headquarters, a double entry procedure was implemented. Six data entry operators were hired by NBS to perform the second data entry for the paper questionnaires into the CSPro-based data entry system for all questionnaires administered. A comparison between the entered values in the field based data entry and headquarters based data entry was conducted and any discrepancies in values between the two were flagged for manual inspection of the physical questionnaire and corrected. The application of the third level of data consistency validation further allowed for the assessment of the quality of the entry work performed by both the field entry staff and the headquarters based entry staff. Regular feedback was supplied to data entry staff resulting in improved quality where needed and overall efficiency. Additional data cleaning was conducted as the final stage of the data processing. Further adjustment of the data post-entry was conducted under the principle of absolute certainty where adjustments must be evidence based and correction values true beyond a reasonable doubt. As such, the resulting final datasets may still contain some inconsistencies and outliers. Handling of these values is thus left entirely to the data user. Throughout the data processing system versions of the data are archived at all key steps and all checking and cleaning syntax documented and archived.
The users shall not take any action with the purpose of identifying any individual entity (i.e. person, household, enterprise, etc.) in the micro dataset(s). If such a disclosure is made inadvertently, no use will be made of the information, and it will be reported immediately to FAO
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National Bureau of Statistics (NBS) [Tanzania]. 2013. Tanzania National Panel Survey Report (NPS) - Wave 3, 2012 - 2013. Dar es Salaam, Tanzania: NBS. (www.nbs.go.tz)
Disclaimer and copyrights
The user of the data acknowledges that the original collector of the data, the authorized distributor of the data, and the relevant funding agency bear no responsibility for use of the data or for interpretations or inferences based upon such uses