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.
Mountains cover about 20% of the Earth's surface and are found on all continents and in all oceans. The movement of the earth's crust by folding, breaking into large blocks, lifting upwards to form a dome, or cracking due to volcanic activity forms mountain ranges.