dmeb

  val xs = List(1, 2, 3) // i.e. 1 -> 2 -> 3 -> Nil
  val ys = 42 :: xs  // i.e. 42 -> xs

  val xs = List(1,2,3) // 1 -> 2 -> 3 -> Nil
  val zs = xs ++ List(42) // 1 -> 2 -> 3 -> 42 -> Nil 

  1) Very large gaps between average wages of whites and blacks
  2) Controlling for ability* erases almost all the disparity 
  3) White and black infants have same distribution of ability  
  4) Large disparity in ability develops between white and blacks by age 18