Is metacognition an affective, cognitive, or behavioural variable?
It seems like there are a lot of ideas out there as to what metacognition really is.  Having done my MS thesis in understanding how people learn in engineering programs, I typically think about metacognition as "knowing how to learn."  It's typically a goal of engineering education to teach students these skills.  

Therefore, I would say it's mostly a cognitive variable, but it's also a behavior because it's a set of habits about how one thinks.  How are you planning to measure metacognition?  And why inductive reasoning?  Why not critical thinking in general?