Ted Robert Gurr

And it started off on a long-term collaboration between us.

And we put together, worked with a data set of Professor Ted Gurr, who had all the ethnic groups in the world and wanted to know the degree to which they would be at war with each other.

Jim and I worked with this data for a long time and realized we'll never get over a problem of selection bias.

That is, of putting ethnic groups in the data set based upon the degree to which they had some influence over peace or war.