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This dissertation was written as a part of the MSc in Mobile and Web Computing at the International Hellenic University. The aim of this work is to investigate if user’s demographics data and ratings entropy0 scores can have an impact on addressing the cold start problem in collaborative filtering. We propose four collaborative movie recommender systems that use ask - to - rate techniques by displaying movies to users for rating. The implementation of the aforementioned systems was done in Python 3.6 programming language, developing four independent scripts that display movies for rating using different ask - to - rate techniques: random choice of movies, demographic based, entropy0 based , mix of demographic and entropy0 based. In the evaluation we have taken into consideration both the accuracy of the predictions but also the user effort. The results have shown that there is (almost) a tie for the first place between demographic - based and entropy0 - based systems both in terms of user preference score but also in terms of user’s effort (entropy0 based system is only margin ally better) . Furthermore, we can also see that the system with the combination of demographics and entropy0, is slightly better (in terms of user preference score ) than the basic (random selection), even if the user effort is much higher. Finally, for a future work we can use a movie - set with newer movies or a completely different dataset with another type of products like electronic devices, books etc. Moreover, a mobile implementation can make recommender systems even more useful and also valuable.