Significance+Level

Significance Level (TBR) (GWU EMSE-271)
Index | Topics (Logical Lectures) | Lectures | Problems | Readings | Nomenclature | Concepts

"In statistics, a result is called **statistically significant** if it is unlikely to have occurred by chance.

"The use of the word //significance// in statistics is different from the standard one, which suggests that something is important or meaningful. For example, a study that included tens of thousands of participants might be able to say with very great confidence that people of one race are more intelligent than people of another race by 1/20th of an IQ point. This result would be statistically significant, but the difference is small enough to be utterly unimportant. Many researchers urge that tests of significance should always be accompanied by effect size statistics, which approximate the size and thus the practical importance of the difference.

"The amount of evidence required to accept that an event is unlikely to have arisen by chance is known as the **significance level** or critical p-value: in traditional Fisherian statistical hypothesis testing, the p-value is the probability conditional on the null hypothesis of the observed data or more extreme data. If the obtained p-value is small then it can be said either the null hypothesis is false or an unusual event has occurred. It is worth stressing that p-values do not have any repeat sampling interpretation.- [|Wikipedia]


 * Sources:**
 * Statistical significance. (2009, December 4). In //Wikipedia, The Free Encyclopedia//. Retrieved 21:55, December 8, 2009, from []
 * EMSE 271, Fall 2009