They both worked until death
The use of demographic data helps the government determine the needs for the citizens. An example of this can be seen with the citizens of the south side of Chicago. Crime is rampant and the city has the highest murder rate in the US. Demographic data can help by determining specific areas in the city where the crimes and killings are occurring, provide opportunities for the citizens to have safe places to stay, offer educational programs to promote success within the community, and provide additional services like hiring more law enforcement, to keep the people safe. This is only a few ideas how demographics can help citizens.
The Yalta conference was a meeting of leaders of world powers to discuss world war 2 action and the separation of territories in post war society. It let to the cold war because it enabled division into completely different blocks that could work independently of each other and fight for their own supremacy. It had to be allowed because the world powers would not have agreed to work together the other way around.