How do researchers determine what is true based on the data they collect? This question is one of the central concerns of statistics, which uses mathematical models to draw useful conclusions about the real world.

Mexico, officially the United Mexican States, is a federal constitutional republic in North America. Working may require a work visa, which is difficult to get if you want to freelance for a short time. Most of the government-funded universities in major cities (state capital) have short courses on history, gastronomy, and cultural subjects, and most of them are almost free.