Which of the following is the most subjective method of educational psychology?

Introspection is the most subjective method of educational psychology. It is the oldest method of educational psychology. The word 'introspection' has been derived from two Latin words, 'intro' meaning 'withing' and 'spiere' meaning to 'look'. Therefore introspection implies 'self observation', or in other words, to experience one's own mental state i.e., to observe, analyse and report one's own feelings.