There will be serious changes for Facebook advertisers using website conversions for measurement and/or optimization. Facebook is implementing something it calls Aggregated Event Measurement, which is its answer to Private Click Measurement, and designed to provide partial and/or modeled reporting when data is restricted, aggregated, or delayed. Facebook is also eliminating some Click-Through attribution windows, almost all View-Through attribution windows, and conversion lift measurement. Finally, Facebook is advising advertisers that audiences sourced from Pixel data will be smaller.