In the hypothesis testing approach of Jerzy Neyman and Egon Pearson, a null hypothesis is contrasted with an alternative hypothesis, and the two hypotheses are distinguished on the basis of data, with certain error rates. Proponents of each approach criticize the other approach.
In geography, relief refers to the highest and lowest elevation points in an area. Mountains and ridges are typically the highest elevation points, while valleys and other low-lying areas are the lowest. Relief is essential to understanding the topography of an area.
There are three main types of mountains. block mountains formed by sections of the earth's crust that have been tilted or lifted up by the movement of two close fault lines, large cracks in the earth's surface. These are usually smaller than other types of mountains and are often separated by valleys.