Hi Lewis, I guess that this documentation will respond to your question.
https://help.mypurecloud.com/articles/configure-the-service-level-calculation/
Note: This setting applies retroactively. When you change this setting, the service level data for past dates in views and future reports update to reflect the change. The data does not update in any reports that have already run.
Att,
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Breno Canyggia Ferreira Marreco
https://www.linkedin.com/in/brenocfm-40b62182/------------------------------