NCHS - Teen Birth Rates for Age Group 15-19 in the United States by County

This data set contains estimated teen birth rates for age group 15–19 (expressed per 1,000 females aged 15–19) by county and year.

DEFINITIONS

Estimated teen birth rate: Model-based estimates of teen birth rates for age group 15–19 (expressed per 1,000 females aged 15–19) for a specific county and year. Estimated county teen birth rates were obtained using the methods described elsewhere (1,2,3,4). These annual county-level teen birth estimates “borrow strength” across counties and years to generate accurate estimates where data are sparse due to small population size (1,2,3,4). The inferential method uses information—including the estimated teen birth rates from neighboring counties across years and the associated explanatory variables—to provide a stable estimate of the county teen birth rate.
Median teen birth rate: The middle value of the estimated teen birth rates for the age group 15–19 for counties in a state.
Bayesian credible intervals: A range of values within which there is a 95% probability that the actual teen birth rate will fall, based on the observed teen births data and the model.

NOTES

Data on the number of live births for women aged 15–19 years were extracted from the National Center for Health Statistics’ (NCHS) National Vital Statistics System birth data files for 2003–2015 (5).

Population estimates were extracted from the files containing intercensal and postcensal bridged-race population estimates provided by NCHS. For each year, the July population estimates were used, with the exception of the year of the decennial census, 2010, for which the April estimates were used.

Hierarchical Bayesian space–time models were used to generate hierarchical Bayesian estimates of county teen birth rates for each year during 2003–2015 (1,2,3,4).

The Bayesian analogue of the frequentist confidence interval is defined as the Bayesian credible interval. A 100*(1-α)% Bayesian credible interval for an unknown parameter vector θ and observed data vector y is a subset C of parameter space Ф such that
1-α≤P({C│y})=∫p{θ │y}dθ,
where integration is performed over the set and is replaced by summation for discrete components of θ. The probability that θ lies in C given the observed data y is at least (1- α) (6).

County borders in Alaska changed, and new counties were formed and others were merged, during 2003–2015. These changes were reflected in the population files but not in the natality files. For this reason, two counties in Alaska were collapsed so that the birth and population counts were comparable. Additionally, Kalawao County, a remote island county in Hawaii, recorded no births, and census estimates indicated a denominator of 0 (i.e., no females between the ages of 15 and 19 years residing in the county from 2003 through 2015). For this reason, Kalawao County was removed from the analysis. Also , Bedford City, Virginia, was added to Bedford County in 2015 and no longer appears in the mortality file in 2015. For consistency, Bedford City was merged with Bedford County, Virginia, for the entire 2003–2015 period. Final analysis was conducted on 3,137 counties for each year from 2003 through 2015. County boundaries are consistent with the vintage 2005–2007 bridged-race population file geographies (7).

本数据集包含对15至19岁年龄组（以每千名15至19岁女性为基准）的青少年生育率的估计值，数据按县和年份划分。

### 定义

* 青少年生育率估计值：针对特定县和年份，采用模型估计15至19岁年龄组的青少年生育率（以每千名15至19岁女性为基准）。利用 elsewhere 中描述的方法（1,2,3,4）获得了县一级的青少年生育率估计值。这些年度县一级的青少年生育率估计值通过跨县和跨年的数据“借力”，以生成准确估计，尤其是在因人口规模较小而数据稀疏的情况下（1,2,3,4）。推断方法利用包括来自相邻县历年的青少年生育率估计值及其相关解释变量在内的信息，以提供对县一级青少年生育率的稳定估计。
* 青少年生育率中位数：一个州内各县的15至19岁年龄组青少年生育率估计值的中位数。
* 贝叶斯可信区间：基于观察到的青少年生育数据及模型，存在95%概率认为实际青少年生育率将落在此范围内的值域。

### 说明

从2003年至2015年，15至19岁女性活产数的数据来源于美国国家健康统计中心（NCHS）的国家生命统计系统出生数据文件（5）。

人口估计值来自由NCHS提供的跨普查和普查后桥梁种族人口估计值文件。对于每个年份，使用了7月份的人口估计值，但在十年一次的普查年份2010年，使用了4月份的估计值。

在2003年至2015年期间，使用了分层贝叶斯时空模型来生成县一级青少年生育率每年的分层贝叶斯估计值（1,2,3,4）。

贝叶斯置信区间是频率主义者置信区间的贝叶斯对应物。对于未知参数向量θ和观察数据向量y的100*(1-α)%贝叶斯可信区间是参数空间Φ的子集C，使得
1-α≤P({C│y})=∫p{θ │y}dθ，其中积分是在集合上进行的，对于θ的离散组成部分，积分被求和所替代。在观察数据y给定的条件下，θ落在C中的概率至少是(1- α)（6）。

在2003年至2015年期间，阿拉斯加的县边界发生了变化，新县成立，一些县被合并。这些变化反映在人口文件中，但未反映在出生率文件中。因此，将阿拉斯加的两个县合并，以便出生和人口计数可比。此外，夏威夷的一个偏远岛屿县Kalawao县没有记录出生，人口普查估计表明分母为0（即，2003年至2015年间，县内没有15至19岁的女性）。因此，Kalawao县被排除在分析之外。此外，2015年弗吉尼亚州的Bedford City被并入Bedford县，并在2015年的死亡率文件中不再出现。为了保持一致性，Bedford City在整个2003年至2015年期间与弗吉尼亚州的Bedford县合并。最终分析是在3,137个县每年的基础上进行的。县边界与2005年至2007年桥梁种族人口文件的地理信息保持一致（7）。