A combination of human and physical factors effect the distribution of population. Human factors include politics, economics, and culture. Physical factors include the climate, landforms, and bodies of water. The three methods for calculating population densities are arithmetic, physiological, and agricultural. Arithmetic density tell us how many people are living per square of land, while physiological density tells us how many people are living per square of arable land. Agricultural density is calculated by diving number of farmers by square of arable land. A low agricultural density shows the development of a country and the availability of technology which allows for a more efficient agriculture and vise versa.