Paradoxical effect of triangulation? - Hornowska, Elżbieta; Brzezińska, Anna Izabela; Kaliszewska-Czeremska, Katarzyna; Appelt, Karolina; Rawecka, Joanna; Bujacz, Aleksandra (Educational Research Institute)
Keywords: convergent validity; discriminant validity; inquiry approach; reliability; sources of data; triangulation