To catch a terrorist - Can ethnic profiling work?

lihakakku

Has anybody read the article by William H. Press concerning profiling: http://www.nr.com/whp/Significance_T...ATerrorist.pdf ?
I m just wondering how can selection probability q_i be expressed as q_i=M*p_i because this gives for q_i bigger values than 1.
My other concern was how is it shown that equation (5) is always smaller than equation (3)?
I have to wonder if there are some assumptions made about p_i's and q_i's between the lines that I can not see...I would really much appreciatite help or any discussion about this interesting topic!