Dr. Martha Stout presents extensive amounts of information based on research. in essence, the 4 she refers to is not a part of the 1 in 25 but apart of the entire population that walks among us.
This book puts questions out on the table and the reader thinks about the various natures of sociopaths which leads them into thinking that people around them are all sociopaths. She is very unorganized in her writing but presents lots of interesting information about these ruthless creatures.