Q2. [4 marks] After learning from an analysis that the correlation between the amount of grey hair a person is highly (positively) correlated with the amount of money (including all investments and assets etc.) one has, Joe quickly dyed his hair to white (with some grey shades) because he wanted to be rich.

a) Briefly discuss if his comment is valid. [2]

b) Suggest a (lurking) variable that might have a direct effect on both of the variables of interest. Justify your answer. 0 mark if no justification. [2]