Because of the earths rotation around the sun.
Two major quantitative research tools which are being used by sociologists would be graph theory - graph theory is a special area of mathematics which gets used in social network theory and is an interesting tool to use. Another are questionnaires which represent the bulk of sociologist empirical research.
I believe the answer is: somewhat more
When a person make a public virginity-until-marriage pledge, they tend to be more likely to feel some sort of social pressure to follow on their words in fear of being seen as a hypocrites by other peers. This would indeed improve their likelihood to stay a virgin, But the effect of the social pressure tend to diminish over time
Map. Earth. Landscape. Country.
