I am a cystic fibrosis research doctor and am trying analyse multiple visual analogue scale results in order to identify when a patgient's symptoms have worsened sufficiantly to warrant treatment. I have data from each patient on alternate days for a year and I think that the CUSUM technique would be a useful way to show when a patient's sympotoms have reached a treshold to warrant treatment. Does anyone know how I can use cusum in Excel? Or perhaps any other ideas? Thank you