Before revision:  What follows, the reliance on these implicit weights can have serious consequences for applied work . I illustrate some of these issues in four empirical applicationsfrom different fields of economics. I also develop a weighted least squares correction and simple diagnostic tools that applied researchers can use to avoid potential biases  .
After revision:  What follows, the reliance on these implicit weights can have serious consequences for applied work , as I illustrate with two well-known applications. I develop simple diagnostic tools that applied researchers can use to avoid potential biases .