These magma plumes rise to the surface and form chains of volcanoes. Composite volcano magma contains more silica, SiO 2, than that of a shield volcano and is therefore stickier (more viscous). This stickiness plugs up the volcano, causing pressure to build-up. The result is an explosive, dangerous eruption.
It results in a biased sample, a non-random sample of a population (or non-human factors) in which all individuals, or instances, were not equally likely to have been selected. If this is not accounted for, results can be erroneously attributed to the phenomenon under study rather than to the method of sampling.
Noun. 1) Strict definition: An irrational bias towards members of a racial background. The bias can be positive (e.g. one race can prefer the company of its own race or even another) or it can be negative (e.g. one race can hate another). To qualify as racism, the bias must be irrational.