TZA_2012_NPS-R3_v01_M
National Panel Survey 2012-2013
Wave 3
Name | Country code |
---|---|
Tanzania | TZA |
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.
Sample survey data [ssd]
Households and individuals.
The 2012-13 NPS covers the following topics:
HOUSEHOLD: Household identification; Survey staff details; Household member roster; Eduaction, Health, Labour; Food outside the household; Subject welfare; Food security; Housing, 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.
AGRICULTURE:Household roster; Plot roster; Plot details; Crops by plot; Crops - Household totals ( production and sales); Permanent crops by plot; Permanent crops - Household totals (production and sales); Input vouchers; Outgrower schemes and contract farming; Processed agricultural products and agricultural by-products; Farm implents and machinery extension; Extension.
LIVESTOCK AND FISHERY: Household member roster; Livestock stock; Animal health; Feed, water, housing, breeding; Livestock-labour; Milk; Animal power & dung; Other livestock products; Fishery- Household labour; Fishery- Hired labour; Fishing inputs; Fisheries output; Fish trading.
COMMUNITY: Community identification; Survey staff details; Access to basic services; Investments projects; Land use; Demographics, land & livestock, Market prices; Local units.
Topic |
---|
Agriculture & Rural Development |
Health |
Social Development |
Representative at the national, urban/rural and major ago-ecological zones levels.
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.
Name | Affiliation |
---|---|
National Bureau of Statistics | Ministry of Finance,Tanzania |
Name | Affiliation | Role |
---|---|---|
Ministry of Agriculture, Food Security and Cooperatives | Government of Tanzania | Technical assistance |
Ministry of Finance | Government of Tanzania | Technical assistance |
Millennium Challenge Account-Tanzania | Government of Tanzania | Technical assistance |
World Bank | Technical assistance | |
United Nations Fund of Development Program | Technical assistance |
Name | Role |
---|---|
European Commission | Funding |
World Bank | Funding |
Name | Role |
---|---|
NPS Technical Committee | Technical Advice |
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.5 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.
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 TZNPS 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.
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 sourcesshowed 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 firststage 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. Details on the methodology can be found in the paper: Himelein, Kristen. 2013. “Weight Calculations for Panel Surveys with Subsampling and Split-off Tracking.” Statistics and Public Policy, vol (1), pp40-45.
The third round of the NPS consists of four survey instruments: a Household Questionnaire, Agriculture Questionnaire, Livestock/Fishery Questionnaire, and a Community Questionnaire. Each of the NPS questionnaires were developed in collaboration with line ministries and donor partners, including the Technical Committee, over a period of several months. The NBS solicited feedback from various stakeholders in regards to survey content and design paying due consideration to comparability with previous panel rounds.
Piloting of the NPS 2012/2013 instruments took place in the Tanga region in July 2012 in conjunction with supervisor training. After piloting, the questionnaires were further revised and finalized in September 2012. Interviewer manuals were developed with detailed instructions for field staff during training and as the main reference guide for the survey over the course of the fieldwork.
The questionnaires for NPS 2012-13 are available in English and Swahili.
Start | End |
---|---|
2012-10 | 2013-11 |
2012/10 - 2013/10
Name | Affiliation |
---|---|
National Bureau of Statistics | Ministry of Finance, Tanzania |
The data were collected using paper questionnaires that were key entered in the field concurrently with the data collection.
Preparations:
The field staff was trained in Morogoro in September 2012 over a period of four weeks with enumerator and data entry training done concurrently. During a standard training week, four days were spent in classroom, and one day in field training. On each Saturday of the training month, the field staff was debriefed on the previous day’s field exercise and what they had learned over the previous week. Over the four week training period, the field staff spent one week on the Household questionnaire, Agricultural questionnaire, Livestock/Fishery questionnaire and tracking, and field practice respectively. Over the training period, three tests were administered to the field teams. The goal was to gain feedback from the training sessions and to select the enumerators. Overall, there were 55 enumerator candidates, with 48 being selected. At the end of the training the enumerators were provided Kiswahili field manuals.
Prior to the training period, two pilot tests were conducted. In mid-July 2012, the new questionnaire instruments were piloted in Tanga. In early August 2012, the tracking pilot was conducted in Morogoro to test revisions to the tracking forms. Select households from an MCAT survey conducted in 2010 were revisited to provide the team supervisors practice with conducting tracking during fieldwork. After the pilots, extensive discussion and revisions were conducted with the participation of all team supervisors.
Field Work:
The main data collection began in October 2012 and finished in October 2013, with tracking fieldwork continuing until the end of November 2013. The survey was primarily implemented by seven mobile field teams, each composed of: one supervisor, five or six enumerators, one data entry technician, and one driver. In addition, there were also two dedicated mobile tracking teams that were each composed of: one supervisor, two enumerators, one data entry technician and one driver.
In NPS 2008/2009, enumeration areas (EAs) were selected and then households within those EAs were selected for the sample. For the third round, households from the second round were grouped into clusters. These third round clusters are very similar to the EAs from the second round in that they both consist of primarily the same households. However, each cluster also included both distance and local tracking cases from the second round that reside nearby but not in the same exact EA as the other households in that cluster. Efforts were made in the design of the clusters to be able to maintain the timing of the previous rounds survey.
Field teams visited each cluster for between 4-5 days. The questionnaires were administered to the selected households over the course of that time. This allowed the field team to make return visits to the household to complete the entire Household questionnaire, Agriculture questionnaire for farming households, and Livestock/Fisheries questionnaire for households engaged in livestock or fisheries activities. To ensure the depth and quality of each section of the survey, the questionnaire was administered across multiple respondents to the most knowledgeable about each topic. For all of the sampled households, areas of all owned and/or cultivated agricultural plots were measured via GPS unless the household refused, the terrain was too difficult, or if the plot was more than 1 hour from the location of the household. Anthropometric measurements were taken for all individuals that were at home, not too ill, and willing to participate.
Tracking:
Tracking consists of three stages: (1) determine the current status of the households and members of the households from the previous survey; (2) determine the location of any households that have moved together with all its members to a new location; and (3) determine the location of any eligible members who have moved from their household from either NPS 2008/2009 or NPS 2010/2011 to a new location. Eligibility for tracking of households and members was determined prior to the implementation of the survey. Members eligible for tracking were those who are over the age of 15 and not a live-in house servant. Any panel members not meeting this criteria were not tracked and were only included in the data when located and interviewed with an eligible member. Households eligible for tracking were those that moved to a new location within Tanzania. If a household moved to a different country, it was not tracked.
If an entire household had moved from the original residence, teams were required to complete a “T-1” form designed to capture relevant information from key informants on the whereabouts of the household. The T-1 form contains information that would enable tracking of household to its new location. If a member or members of the household have moved from the original household, a “T-2” form was completed by the teams. Similar to the T-1, a T-2 form contains information on the location of the member(s) who have moved from the household. Once the tracking targets had been located, teams were required to interview the household as consistent with the eligibility requirements.
Within the tracking protocol, there are local and distance tracking cases. Local and distance tracking applies to both households and individuals. Local tracking is defined as cases where the tracking target is within one hour driving distance from the original cluster and at least one tracking member from the household is eligible for tracking. For local tracking cases, the teams are required to interview the tracking target before leaving the original cluster. Distance tracking occurs when the tracking target resides in a location that is more than one hour driving distance from the original cluster. In this case, the teams fill out the appropriate tracking form and send the information to NBS headquarters. Once at NBS headquarters, the distance tracking case is given to one of the two dedicated tracking teams, who are then responsible for locating that household and conducting the interview.
Often households and members which have moved from their previous dwelling or household have relocated a great distance from their previous interview location. Given the inefficiency in searching for these members on a case by case basis across the country as they occur, field teams were not required to track households and members deemed to be too far away from the original location. Information on these cases was key entered and sent electronically to the NBS headquarters, compiled, and reviewed. After review an optimal tracking route was generated to guide the specialized tracking teams.
Distance tracking was divided into rounds with each round lasting approximately two months. The first round began interviews three months after the beginning of fieldwork to allow enough time to accumulate a sufficient number of distance tracking targets. At the start of each round, the new distance tracking cases would be compiled and grouped into geographic regions. The schedules for the two dedicated tracking teams for each round was determined by which geographic regions had the most distance tracking targets Any tracking target not located after each round would remain in the pool to be visited during the subsequent rounds, in addition to any new tracking cases that had accumulated in the intervening months. In addition, the regular field teams also sporadically would perform tracking within their interview regions if the distance tracking target resided in or very close to a cluster on their fieldwork schedule. Finally, following the completion of the main fieldwork activities, four dedicated tracking teams were dispatched to interview the remaining cases.
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.
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.
Tanzania National Bureau of Statistics
Tanzania Natiopnal Bureau of Statistics
http://www.nbs.go.tz/tnada/index.php/catalog/29
Cost: None
Name | Affiliation | URL | |
---|---|---|---|
National Bureau of Statistics | Ministry of Finance, Tanzania | www.nbs.go.tz | dg@nbs.go.tz |
Is signing of a confidentiality declaration required? | Confidentiality declaration text |
---|---|
yes | The Primary Data Investigator undertakes that no attempt will be made to identify any individual person, family, business, enterprise or organization. If such a unique disclosure is made inadvertently, no use will be made of the identity of any person or establishment discovered and full details will be reported to the NBS. The identification will not be revealed to any other person not included in the Data Access Agreement. |
The dataset has been anonymized and is available as a Public Use Dataset. It is accessible to all for statistical and research purposes only, under the following terms and conditions:
The original collector of the data, the National Bureau of Statistics, and the relevant funding agencies bear no responsibility for use of the data or for interpretations or inferences based upon such uses.
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)
Name | Affiliation | URL | |
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Director General | dg@nbs.go.tz | http://nbs.go.tz/index.php?option=com_contact&view=contact&id=1&Itemid=69 | |
LSMS Data Manager | The World Bank | lsms@worldbank.org | surveys.worldbank.org/lsms |
DDI_TZA_2012_NPS-R3_v01_M_WB
Name | Affiliation | Role |
---|---|---|
Development Economics Data Group | The World Bank | Documentation of the DDI |
2015-04-24
Version 01 (April 2015)
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