National Panel Survey 2008-2015, Uniform Panel Dataset - Tanzania

Abstract
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Panel data possess several advantages over conventional cross-sectional and time-series data, including their power to isolate the effects of specific actions, treatments, and general policies often at the core of large-scale econometric development studies. While the concept of panel data alone provides the capacity for modeling the complexities of human behavior, the notion of universal panel data – in which time- and situation-driven variances leading to variations in tools, and thus results, are mitigated – can further enhance exploitation of the richness of panel information.

This Basic Information Document (BID) provides a brief overview of the Tanzania National Panel Survey (NPS), but focuses primarily on the theoretical development and application of panel data, as well as key elements of the universal panel survey instrument and datasets generated by the four rounds of the NPS. As this Basic Information Document (BID) for the UPD does not describe in detail the background, development, or use of the NPS itself, the round-specific NPS BIDs should supplement the information provided here.

The NPS Uniform Panel Dataset (UPD) consists of both survey instruments and datasets, meticulously aligned and engineered with the aim of facilitating the use of and improving access to the wealth of panel data offered by the NPS. The NPS-UPD provides a consistent and straightforward means of conducting not only user-driven analyses using convenient, standardized tools, but also for monitoring MKUKUTA, FYDP II, and other national level development indicators reported by the NPS.

The design of the NPS-UPD combines the four completed rounds of the NPS – NPS 2008/09 (R1), NPS 2010/11 (R2), NPS 2012/13 (R3), and NPS 2014/15 (R4) – into pooled, module-specific survey instruments and datasets. The panel survey instruments offer the ease of comparability over time, with modifications and variances easily identifiable as well as those aspects of the questionnaire which have remained identical and offer consistent information. By providing all module-specific data over time within compact, pooled datasets, panel datasets eliminate the need for user-generated merges between rounds and present data in a clear, logical format, increasing both the usability and comprehension of complex data.

Geographic coverage
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Designed for analysis of key indicators at four primary domains of inference, namely: Dar es Salaam, other urban, rural, Zanzibar.

Analysis unit
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- Households
- Individuals

Universe
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The universe includes all households and individuals in Tanzania with the exception of those residing in military barracks or other institutions.

Kind of data
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Sample survey data [ssd]

Sampling procedure
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While the same sample of respondents was maintained over the first three rounds of the NPS, longitudinal surveys tend to suffer from bias introduced by households leaving the survey over time; i.e. attrition. Although the NPS maintains a highly successful recapture rate (roughly 96% retention at the household level), minimizing the escalation of this selection bias, a refresh of longitudinal cohorts was done for the NPS 2014/15 to ensure proper representativeness of estimates while maintaining a sufficient primary sample to maintain cohesion within panel analysis. A newly completed Population and Housing Census (PHC) in 2012, providing updated population figures along with changes in administrative boundaries, emboldened the opportunity to realign the NPS sample and abate collective bias potentially introduced through attrition.

To maintain the panel concept of the NPS, the sample design for NPS 2014/2015 consisted of a combination of the original NPS sample and a new NPS sample. A nationally representative sub-sample was selected to continue as part of the “Extended Panel” while an entirely new sample, “Refresh Panel”, was selected to represent national and sub-national domains. Similar to the sample in NPS 2008/2009, the sample design for the “Refresh Panel” allows analysis at four primary domains of inference, namely: Dar es Salaam, other urban areas on mainland Tanzania, rural mainland Tanzania, and Zanzibar. This new cohort in NPS 2014/2015 will be maintained and tracked in all future rounds between national censuses.

Mode of data collection
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Face-to-face [f2f]

Research instrument
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The format of the NPS-UPD survey instrument is similar to previously disseminated NPS survey instruments. Each module has a questionnaire and clearly identifies if the module collects information at the individual or household level. Within each module-specific questionnaire of the NPS-UPD survey instrument, there are five distinct sections, arranged vertically: (1) the UPD - “U” on the survey instrument, (2) R4, (3), R3, (4) R2, and (5) R1 – the latter 4 sections presenting each questionnaire in its original form at time of its respective dissemination.

The uppermost section of each module’s questionnaire (“U”) represents the model universal panel questionnaire, with questions generated from the comprehensive listing of questions across all four rounds of the NPS and codes generated from the comprehensive collection of codes. The following sections are arranged vertically by round, considering R4 as most recent. While not all rounds will have data reported for each question in the UPD and not each question will have reports for each of the UPD codes listed, the NPS-UPD survey instrument represents the visual, all-inclusive set of information collected by the NPS over time.

The four round-specific sections (R4, R3, R2, R1) are aligned with their UPD-equivalent question, visually presenting their contribution to compatibility with the UPD. Each round-specific section includes the original round-specific variable names, response codes and skip patterns (corresponding to their respective round-specific NPS data sets, and despite their variance from other rounds or from the comprehensive UPD code listing)4.

摘要
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面板数据相较于传统的横截面数据和时间序列数据，具有多方面的优势，尤其是能够隔离特定行动、治疗和一般政策的影响，这些往往是大规模计量经济学发展研究的核心。尽管面板数据的概念本身便具备了模拟人类行为复杂性的能力，但普遍面板数据——其中时间与情境驱动的差异得以减轻，从而降低工具和结果的变化——进一步提升了面板信息的丰富性利用。

本基本信息文件（BID）对坦桑尼亚国家面板调查（NPS）进行了简要概述，但主要聚焦于面板数据理论的发展与应用，以及NPS四轮调查所生成的普遍面板调查工具和数据集的关键要素。鉴于本基本信息文件（BID）并未详细描述NPS的背景、发展或使用情况，因此特定轮次的NPS BID应补充此处提供的信息。

NPS统一面板数据集（UPD）由调查工具和数据集组成，经过精心设计和编排，旨在促进对NPS所提供丰富的面板数据的利用和访问。NPS-UPD提供了进行用户驱动分析的一致且简便的途径，不仅使用方便的标准工具，而且可以监测NPS报告的MKUKUTA、FYDP II和其他国家级发展指标。

NPS-UPD的设计将NPS的四轮调查——NPS 2008/09（R1）、NPS 2010/11（R2）、NPS 2012/13（R3）和NPS 2014/15（R4）——结合为模块特定的调查工具和数据集。面板调查工具便于时间上的比较，其中的修改和差异易于识别，同时问卷中保持一致的、提供一致信息的部分也一目了然。通过在紧凑的、汇总的数据集中提供所有模块特定的历史数据，面板数据集消除了用户在轮次间生成合并的需求，并以清晰、逻辑的方式呈现数据，从而提高了数据的可用性和理解性。

地理覆盖范围
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设计用于分析四个主要推理领域的关键指标，即：达累斯萨拉姆、其他城市、农村、桑给巴尔。

分析单元
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- 家庭
- 个人

总体
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总体包括所有居住在坦桑尼亚的家庭和个人，但排除了居住在军营或其他机构的人员。

数据类型
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样本调查数据 [ssd]

抽样程序
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尽管NPS在第一、二、三轮中保持了相同的受访者样本，但纵向调查往往会受到随着时间的推移而退出调查的家庭所引入的偏差的影响；即：流失。尽管NPS保持了极高的重捕率（大约96%的家庭水平保留率），最大限度地减少了这种选择偏差的加剧，但在2014/15年的NPS中进行了纵向群体的更新，以确保估计的适当代表性，同时保持足够的主要样本以维护面板分析中的连贯性。2012年完成的新的人口和住房普查（PHC），提供了更新的人口数据以及行政区划的变化，为重新调整NPS样本和减轻通过流失可能引入的集体偏差提供了机会。

为了维持NPS的面板概念，NPS 2014/2015年的样本设计由原始NPS样本和新NPS样本的组合组成。选择了一个具有全国代表性的子样本作为“扩展面板”的一部分继续存在，同时选择了一个全新的样本，“刷新面板”，以代表国家和次国家领域。与NPS 2008/2009年的样本类似，“刷新面板”的样本设计允许在四个主要推理领域进行分析，即：达累斯萨拉姆、坦桑尼亚大陆的其他城市地区、坦桑尼亚大陆的农村地区和桑给巴尔。这个新的群体将在国家人口普查之间的所有未来轮次中保持并跟踪。

数据收集方式
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面对面 [f2f]

研究工具
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NPS-UPD调查工具的格式与之前发布的NPS调查工具相似。每个模块都有一个问卷，并明确标识该模块收集个人或家庭层面的信息。在NPS-UPD调查工具的每个模块特定的问卷中，有五个不同的部分，垂直排列：（1）UPD - “U”在调查工具上，（2）R4，（3），R3，（4）R2，和（5）R1 – 后四个部分以各自发布时的原始形式呈现每个问卷。

每个模块问卷的最上面部分（“U”）代表模型普遍面板问卷，其中的问题来自NPS四轮调查中问题的综合列表，代码来自综合收集的代码。以下部分按轮次垂直排列，以R4为最新。虽然UPD中并非所有轮次都会报告每个问题的数据，也并非每个UPD代码都会报告每个问题的数据，但NPS-UPD调查工具代表了NPS在时间上收集的全面信息集。

四个轮次特定的部分（R4、R3、R2、R1）与UPD等效问题对齐，直观地展示了其对UPD兼容性的贡献。每个轮次特定的部分包括原始轮次特定的变量名称、响应代码和跳过模式（对应于各自的轮次特定NPS数据集，尽管它们与其他轮次或综合UPD代码列表存在差异）。