ACS Poverty Status Variables - Tract

This layer shows poverty status by age group. This is shown by tract, county, and state boundaries. This service is updated annually to contain the most currently released American Community Survey (ACS) 5-year data, and contains estimates and margins of error. There are also additional calculated attributes related to this topic, which can be mapped or used within analysis. Poverty status is based on income in past 12 months of survey. This layer is symbolized to show the percentage of the population whose income falls below the Federal poverty line. To see the full list of attributes available in this service, go to the "Data" tab, and choose "Fields" at the top right. Current Vintage: 2015-2019 ACS Table(s): B17020 Data downloaded from: Census Bureau's API for American Community Survey Date of API call: December 10, 2020 National Figures: data.census.gov The United States Census Bureau's American Community Survey (ACS): About the Survey Geography & ACS Technical Documentation News & Updates This ready-to-use layer can be used within ArcGIS Pro, ArcGIS Online, its configurable apps, dashboards, Story Maps, custom apps, and mobile apps. Data can also be exported for offline workflows. For more information about ACS layers, visit the FAQ. Please cite the Census and ACS when using this data. Data Note from the Census: Data are based on a sample and are subject to sampling variability. The degree of uncertainty for an estimate arising from sampling variability is represented through the use of a margin of error. The value shown here is the 90 percent margin of error. The margin of error can be interpreted as providing a 90 percent probability that the interval defined by the estimate minus the margin of error and the estimate plus the margin of error (the lower and upper confidence bounds) contains the true value. In addition to sampling variability, the ACS estimates are subject to nonsampling error (for a discussion of nonsampling variability, see Accuracy of the Data). The effect of nonsampling error is not represented in these tables. Data Processing Notes: This layer is updated automatically when the most current vintage of ACS data is released each year, usually in December. The layer always contains the latest available ACS 5-year estimates. It is updated annually within days of the Census Bureau's release schedule. Click here to learn more about ACS data releases. Boundaries come from the US Census TIGER geodatabases. Boundaries are updated at the same time as the data updates (annually), and the boundary vintage appropriately matches the data vintage as specified by the Census. These are Census boundaries with water and/or coastlines clipped for cartographic purposes. For census tracts, the water cutouts are derived from a subset of the 2010 AWATER (Area Water) boundaries offered by TIGER. For state and county boundaries, the water and coastlines are derived from the coastlines of the 500k TIGER Cartographic Boundary Shapefiles. The original AWATER and ALAND fields are still available as attributes within the data table (units are square meters). The States layer contains 52 records - all US states, Washington D.C., and Puerto Rico Census tracts with no population that occur in areas of water, such as oceans, are removed from this data service (Census Tracts beginning with 99). Percentages and derived counts, and associated margins of error, are calculated values (that can be identified by the "_calc_" stub in the field name), and abide by the specifications defined by the American Community Survey. Field alias names were created based on the Table Shells file available from the American Community Survey Summary File Documentation page. Negative values (e.g., -4444...) have been set to null, with the exception of -5555... which has been set to zero. These negative values exist in the raw API data to indicate the following situations: The margin of error column indicates that either no sample observations or too few sample observations were available to compute a standard error and thus the margin of error. A statistical test is not appropriate. Either no sample observations or too few sample observations were available to compute an estimate, or a ratio of medians cannot be calculated because one or both of the median estimates falls in the lowest interval or upper interval of an open-ended distribution. The median falls in the lowest interval of an open-ended distribution, or in the upper interval of an open-ended distribution. A statistical test is not appropriate. The estimate is controlled. A statistical test for sampling variability is not appropriate. The data for this geographic area cannot be displayed because the number of sample cases is too small.

本图层按年龄组展示贫困状况，以人口普查片区（tract）、县及州界作为地理展示范围。
本服务每年更新一次，纳入最新发布的美国社区调查（American Community Survey, ACS）五年期数据，包含估算值与误差幅度。本服务还包含与该主题相关的额外计算属性，可用于制图或分析工作。
贫困状况基于调查受访者过去12个月的收入情况进行判定。
本图层采用符号化渲染，展示收入低于联邦贫困线的人口占比。
如需查看本服务中所有可用属性的完整列表，请前往「数据（Data）」选项卡，并选择右上角的「字段（Fields）」选项。
当前数据版本：2015-2019年ACS，数据表编号：B17020
数据来源：美国人口普查局美国社区调查应用程序编程接口（API）
API调用日期：2020年12月10日
全国数据：data.census.gov
美国人口普查局美国社区调查（ACS）：调查概况、地理信息与ACS技术文档、新闻与更新
本图层为即用型图层，可在ArcGIS Pro、ArcGIS Online、其可配置应用程序、仪表板、故事地图（Story Maps）、自定义应用程序及移动应用中使用。
数据还可导出用于离线作业流程。
如需了解更多关于ACS图层的信息，请访问常见问题解答（FAQ）页面。
使用本数据时，请注明美国人口普查局与ACS的来源。

美国人口普查局数据说明：
本数据基于抽样调查，存在抽样变异性。由抽样变异性导致的估算值不确定程度通过误差幅度体现。本服务中展示的为90%置信水平的误差幅度。误差幅度可理解为：估算值减去误差幅度与估算值加上误差幅度所构成的区间（即置信上下限）有90%的概率包含真实数值。除抽样变异性外，ACS估算值还存在非抽样误差（关于非抽样变异性的讨论，请参见《数据准确性》一文）。本数据表未体现非抽样误差的影响。

数据处理说明：
本图层会在每年ACS最新版本数据发布时自动更新，通常为每年12月。本图层始终包含最新可用的ACS五年期估算数据，更新时间紧跟美国人口普查局的发布计划，通常在发布数日内完成。点击此处可了解更多关于ACS数据发布的相关信息。
地理边界数据来源于美国人口普查局TIGER地理数据库（TIGER geodatabases）。边界数据与本图层数据同步更新（每年一次），且边界版本与美国人口普查局规定的数据版本完全匹配。本图层使用的普查边界已为制图需求裁剪掉水体及海岸线区域。对于人口普查片区（tract），水体裁剪区域来源于TIGER提供的2010年AWATER（Area Water）边界子集；对于州界与县界，水体及海岸线区域来源于50万比例尺TIGER制图边界形状文件的海岸线数据。数据表格中仍保留原始的AWATER与ALAND字段（单位：平方米）。
州图层共包含52条记录，涵盖美国所有州、华盛顿哥伦比亚特区以及波多黎各。
本数据服务已移除位于海洋等水域区域的无人口普查片区（以99开头的普查片区）。
占比、衍生计数及相关误差幅度均为计算所得值（可通过字段名中的"_calc_"前缀识别），且符合ACS规定的计算规范。字段别名基于美国社区调查汇总文件文档页面提供的表壳文件生成。
原始API数据中的负值（如-4444……）已被设置为空值，但-5555……除外，该类负值已被设置为0。原始API数据中的此类负值用于表示以下情形：
1. 误差幅度列表示：无可用样本观测值或样本观测值过少，无法计算标准误，因此无法得出误差幅度，此时不适合进行统计检验。
2. 无可用样本观测值或样本观测值过少，无法计算估算值；或因中位数估算值落在开放式分布的最低区间或最高区间，无法计算中位数比值。
3. 中位数落在开放式分布的最低区间或最高区间，此时不适合进行统计检验。
4. 估算值已受控，此时不适合进行抽样变异性统计检验。
5. 因样本案例数量过少，无法展示该地理区域的数据。