Counts of Dengue reported in GRENADA: 1969-2012

Project Tycho datasets contain case counts for reported disease conditions for countries around the world. The Project Tycho data curation team extracts these case counts from various reputable sources, typically from national or international health authorities, such as the US Centers for Disease Control or the World Health Organization. These original data sources include both open- and restricted-access sources. For restricted-access sources, the Project Tycho team has obtained permission for redistribution from data contributors. All datasets contain case count data that are identical to counts published in the original source and no counts have been modified in any way by the Project Tycho team. The Project Tycho team has pre-processed datasets by adding new variables, such as standard disease and location identifiers, that improve data interpretabilty. We also formatted the data into a standard data format.Each Project Tycho dataset contains case counts for a specific condition (e.g. measles) and for a specific country (e.g. The United States). Case counts are reported per time interval. In addition to case counts, datsets include information about these counts (attributes), such as the location, age group, subpopulation, diagnostic certainty, place of aquisition, and the source from which we extracted case counts. One dataset can include many series of case count time intervals, such as "US measles cases as reported by CDC", or "US measles cases reported by WHO", or "US measles cases that originated abroad", etc.Depending on the intended use of a dataset, we recommend a few data processing steps before analysis:- Analyze missing data: Project Tycho datasets do not inlcude time intervals for which no case count was reported (for many datasets, time series of case counts are incomplete, due to incompleteness of source documents) and users will need to add time intervals for which no count value is available. Project Tycho datasets do include time intervals for which a case count value of zero was reported.- Separate cumulative from non-cumulative time interval series. Case count time series in Project Tycho datasets can be "cumulative" or "fixed-intervals". Cumulative case count time series consist of overlapping case count intervals starting on the same date, but ending on different dates. For example, each interval in a cumulative count time series can start on January 1st, but end on January 7th, 14th, 21st, etc. It is common practice among public health agencies to report cases for cumulative time intervals. Case count series with fixed time intervals consist of mutually exxclusive time intervals that all start and end on different dates and all have identical length (day, week, month, year). Given the different nature of these two types of case count data, we indicated this with an attribute for each count value, named "PartOfCumulativeCountSeries".

第谷计划（Project Tycho）数据集收录了全球各国上报的传染病病例统计数据。

第谷计划数据整理团队从各类权威来源提取上述病例统计值，这些来源通常为国家或国际卫生主管机构，例如美国疾病控制与预防中心（US Centers for Disease Control，CDC）、世界卫生组织（World Health Organization，WHO）等。上述原始数据来源涵盖开放获取与受限访问两类渠道；针对受限访问来源，第谷计划团队已获得数据提供方的再分发许可。

所有数据集的病例统计数据均与原始发布版本完全一致，未被第谷计划团队以任何形式修改。第谷计划团队还对数据集进行了预处理，新增了标准化疾病标识符与位置标识符等变量，以提升数据的可解释性，并将所有数据统一格式化为标准数据结构。

每份第谷计划数据集针对特定疾病（如麻疹）与特定国家（如美利坚合众国）收录病例统计数据，统计值按时间间隔上报。除病例统计数外，数据集还包含与该统计值相关的属性信息，例如统计地点、年龄分组、亚人群、诊断确定性、感染来源以及数据提取来源等。单个数据集可包含多组病例数时间序列，例如“美国疾病控制与预防中心上报的美国麻疹病例数”、“世界卫生组织上报的美国麻疹病例数”、“境外输入性美国麻疹病例数”等。

根据数据集的使用场景，我们建议在开展分析前完成以下数据处理步骤：
- 处理缺失数据：第谷计划数据集未收录无病例数上报的时间区间（多数数据集的病例数时间序列因源文档不全而存在缺失，用户需自行补充无统计值的时间区间）；不过数据集已包含病例数为0的时间区间。
- 区分累计型与非累计型时间序列：第谷计划数据集内的病例数时间序列可分为“累计型”与“固定间隔型”两类。累计型病例数时间序列包含重叠的统计区间，即所有区间的起始日期相同但结束日期各异，例如某累计统计序列的所有区间均始于1月1日，结束日期分别为1月7日、14日、21日等。公共卫生机构通常采用累计时间区间上报病例数。固定间隔型病例数时间序列则由互斥的时间区间组成，所有区间的起止日期均不相同，但区间长度（日、周、月、年）完全一致。鉴于两类病例数数据的性质差异，我们为每个统计值新增了名为“PartOfCumulativeCountSeries”的属性，用于标识该值所属的序列类型。