The test statistic is calculated to be z = (28.5 - 30)/(8/sqrt(100)) = -1.5/0.8 = -1.875. The P-value for this statistic is Decision theory is also concerned with a second error possible in significance testing, known as Type II error.o achieve a significance level of 0.05 for a two-sided test, the absolute value of the test statistic (| z |) must be greater than or equal to the critical value 1.96 (which corresponds to the level 0.025 for a one-sided test).
The Cambrian explosion, or less commonly Cambrian radiation, was the relatively short evolutionary event, beginning around 542 million years ago in the Cambrian Period, during which most major animal phyla appeared, as indicated by the fossil record.he Cambrian explosion has generated extensive scientific debate. The seemingly rapid appearance of fossils in the âPrimordial Strataâ was noted as early as the 1840s, and in 1859 Charles Darwin discussed it as one of the main objections that could be made against the theory of evolution by natural selection.
The Cambrian spans from 541 million years to 485 million years ago and is the first period of the Paleozoic and of the Phanerozoic Eon. The Cambrian sparks a boom in evolution in an event known as the Cambrian Explosion in which the largest number of creatures evolve in the history of Earth during one period.he Paleozoic Era ended with the largest mass extinction in Earth's history, the PermianâTriassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic to recover. Recovery of life in the sea may have been much faster.