What is the voter participation measure used most often by political scientists?

The voter participation measure shows how big was the turnout, that is, how many of the eligible voters actually voted in a community. The higher the turnout the higher degree of democracy in a country. It is measured because of noticing patterns and predicting future elections, especially when wanting to win an election since you can see who didn't vote and often find out why and change that.

If i remember correctly it was caused by people hurling bodies at a country for some reason and them they all became infected