There are several layers in the UDS Mapper that make use of multiple years of data. Some of these layers show the change in the number of patients from one UDS reporting cycle to another. The 2017-2018 layers show the change in the number of patients in each ZCTA from 2017 to 2018. The 2016-2018 layers show the change in the number of patients in each ZCTA from 2016 to 2018.
Estimates such as American Community Survey (ACS) 2013-2017 five-year estimates are based on data collected over a given time period as opposed to data collected at a single point in time. ACS collects survey information continuously for a specific time period and then aggregates those results over a specific time period (in this case five years). The data are then spread evenly across the entire period represented so that no month or year is over represented.
