Raimo, inasmuch as you may never be a 100% assured that the PhD students you are recruiting may complete, there is a high possibility that operationalising certain processes may help. These include, but are not limited to, casting out a wide recruitment net for interested PhDs, encouraging very enthusiastic and bright candidates to apply, ensuring that the recruitment panel consists of a good range of people with relevant expertise in the area, providing the necessary academic and pastoral support throughout the PhD journey, providing a good working environment, creating and sustaining a community that facilitates fruitful interactions between the new and more established PhD candidates as well as those who have gained academic tenures etc...These processes also help in mitigating against the possibility of non-completions and thereby addressing the challenges embedded in pursuing a PhD. Interesting...

Hi John, thank you for sharing your views. You lifted up many important points. I agree with you that we can't predict the success of the PhD students when we are recruting them. The prosesss that you proposed look good. Some of my colleagues are asking their PhD student candidates to do a systematic and extensive literature review related to the topic of the thesis. If the review is enough good, they accept the candidate as a PhD student. I think that this practice include many benefits.

The most important thing is to choose highly qualified students and exclude the rest

We recruit new PhD students trough entrance examination usually called PET examination followed by performance in the oral examination and aptitude for the research.