I need to estimate the maximum number of concurrent users my application will experience in order to set goals for the software development team.
We have 550 potential users, but modelling of the workload suggest that the number of concurrent users will be considerably less. How do I set a set a sensible goal AND persuade a nervous customer that the goal is realistic?
I have good information about the amount of work that will be performed (records created/updated) over the 5 year life of the application and how this work will vary month to month. I also know the working hours of the users and the average duration of each visit. This tells me that if the expected work per month was spread evenly over each month, there will be an average number of 6.5 concurrent users.
Obviously in real life the number of concurrent users will vary.
Is it reasonable to plug this average of 6.5 concurrent users into a poisson distribution, select a confidence limit (I think I could sell 99%) and derive a target 'maximum" number of concurrent users that will rarely be exceeded.
Is this a valid approach?