Hi Usman Arif,
As far as I know, the rejection rate is low as you already have the nomination certificate from the province (Alberta in your case) when you submit you PR application to CIC.
So I think you should feel confident enough to apply for PR application unless you have any
serious crime records/security concerns/medical issues or problems of your job status (economic stability).
However, what matters is the processing time. Sometime they take really longer processing time than others if they think they have found more work to do on your application.
Good luck with your applications