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== 5.15#h(0.6em)Statistical Literacy


    #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Prerequisites]


      Base Rates #linebreak() 
                 #linebreak()
]


    This #link("http://news.bbc.co.uk/2/hi/americas/1205252.stm")[webpage] gives the FBI list of warning signs for school shooters.


    
=== What do you think?


    Do you think it is likely that someone showing a majority of these signs would actually shoot people in school?


    Fortunately the vast majority of students do not become shooters. It is necessary to take this base rate information into account in order to compute the probability that any given student will be a shooter. The warning signs are unlikely to be sufficiently predictive to warrant the conclusion that a student will become a shooter. If an action is taken on the basis of these warning signs, it is likely that the student involved would never have become a shooter even without the action.