When a filter is applied to a view in Google Analytics, what data is affected?

When a filter is applied to a view in Google Analytics, it affects only the data collected after the filter has been created. Filters are used to modify the data before it is processed and stored in the view. This means that any sessions or interactions that occur after the filter is set up will be processed according to the rules defined by that filter.

For example, if a filter is created to exclude a certain segment of traffic or to include only specific hostname data, only the visits and interactions from that point forward will reflect those changes in the reporting of the view. Data collected prior to the creation of the filter is not altered by it, which is why the options indicating changes to historical data or claiming that all or none of the data is affected are not correct. The nature of filters in Google Analytics ensures they only apply to data entering the system after their implementation, thereby providing a way to focus on the most relevant and current information for analysis.