I.20 Measuring. Joni wants to measure the degree to which male college students belong to the political left. She decides simply to measure the length of their hair–longer hair will mean more left-wing.
(a) Is this method likely to be reliable? Why?
(b) This measurement appears to be invalid. Why?
(c) Nevertheless, it is possible that measuring politics by hair length might have some predictive validity. Explain how this could happen.