gooner pretty much said it all…
For me – there is pretty much only one conversion rate which is { clicks to depositors }
None of the other conversions rates really matter i.e even if you have a 90% conversion from sign up to depositors – you might only have a 1% conversion from clicks to signups as it could be a very targeted promotion or someting.
So only really clicks to depositors count as a proper statistic which is also a level playing field statistic (as many casinos / poker rooms have different criteria for a signup or a validated signup etc etc)