NeighborhoodScout's crime data are always the most recent 'Final, Non-Preliminary' data available as classified by the FBI. It is the most up-to-date and fully-vetted data that is available, with complete national coverage. We insist on using Final, Non-Preliminary data for our analyses and analytics rather than basing our research on preliminary data that may need to be updated or have errors in it.
Because the FBI has to work through data and reporting issues, there is always an 8-10 month lag after the close of a calendar year before the data for that year can be released as Final, Non-Preliminary. For instance, the crime analytics currently on the site represents incidences that occurred in 2017. The FBI released the 2017 raw crime data in September of 2018. Our team then re-ran our analyses, modified our models, and quality-assurance tested before launching the newly updated crime data in December 2018.
The FBI will release the 'Final, Non-Preliminary' 2018 calendar-year crime data in the fall of 2019. Until then, what we are using is the most recent data with complete national coverage as per the FBI database.
You can find more information on Scout's crime data here: https://www.neighborhoodscout.com/about-the-data/crime-rates