I highly recommend getting this app and PsychTypes (by BSM Consulting) together and using them in tandem. Both are excellent and come from sources that have taught me a great deal in depth about the whole subject. In fact this app uses a deeper and more effective version of the personality type model than the other one does. A caveat: the version of the MBTI on this app, like any other version of the MBTI, is only meant to be taken as a first approximation and is right the first time only 70% of the time. (For decades I was mistyped as an INTJ by the MBTI; it took professional counseling for me to figure out that Im in fact an ENFP, as some ENFPs are wannabe INTJs.) The MBTI is really meant to be taken under the administration of someone qualified to give it and to give feedback on how one actually behaves rather than how one thinks he behaves. Thats one reason why Dr. Nardi takes other approaches on this app which may be more helpful in figuring out what type one truly is at the "core".