Hi,
I did the same about 15 years ago, so my stuff is outdated, but I can tell you how I did it.
1) Literature search for 5 day vs. 7 day service for acute stroke
* when I did it, there was strong evidence to provide new patients with assessment, mobilisation, positioning charts/ advise and education for patient and family; there was only very weak evidence for 7 day continuous rehabilitation service for established patients
2) Audit 1: I did an audit and counted the number of new stroke patients that were admitted to our hospital (Fri afternoon to Sunday night) over 3 months
* cannot remember the numbers, but it was somewhere in the lines of 2 - 5
3) Audit 2: I did an audit to investigate what other hospitals (nationwide) offer and how they prioritise
* most hospitals oare only funded for an acute respiratory service; some had a 7 day orthopaedic service for certain patient groups
4) Budget: I did an audit for the last 10 years about how much money was allowed for a general weekend service for the Physiotherapy department
* the budget was pathetic and had not been based on any EBP or hospital best practice guidelines, not even for respiratory :-)

My outcome was that evidence shows that all new Stroke patients should have a Physio screening assessment and immediate education/ basic treatment start on Saturday and on Sunday.
Needless to say that we were told that the budget does not allow for such a service. I have since left, so don't know what the situation is these days.
Regards,
Fyzzio