Thanks for your answers, now I see that there are a lot of factors for no show passengers.
But for my diploma thesis I have to narrow down the no show passenger situation. It is important to get a feeling that x% of the passenger with baggage which is checked in and must be found and unloaded before departure. E. g. I heared that it is really common that delays result from these no show pax. Perhaps, there is a rate of 0,2% of all pax are no show pax... I know it's very difficult but it is so important for me