Try a search for sprinklers and cost benefit analysis in google, you might find something.
Also try the ODPM, Entec undertook a UK Risk Assessment Study of various types of occupancies, using probabilistic analysis this contained UK Statistics.
If you want to undertake a similar exercise for the hospital, get a copy of the following PDF file it explains Quantitative Risk Assessment and although a swedish publication (not the saucy type of publication)
http://www.brand.lth.se/bibl/3101.pdfTaking that Risk = Probability x Consequences in your case the consequences are injuries/fatalities/cost
You might want to show a simple event tree, as shown in the PDF. Assign probabilities to a simple event tree starting with the argument
ignition has occured
detection succesful or not successful
manual suppression successful not succesful
automatic suppression successful not succesful
and assign the consequences to the end of the tree.
Undertake a cost benefit analysis showing the diminishing cost of sprinkler over 25 years.
Your ultimate goal is to demonstrate that the cost/lives saved outweigh the risk. A simple hazard assessment (HTM/FPWR) and failure scenario estimation can demonstrate the need for further measures.
I hope this helps.
