Wiktionary
n. (context statistics English) A measure of how unlikely it is that a result has occurred by chance.
Wikipedia
In statistical hypothesis testing, statistical significance (or a statistically significant result) is attained when a p-value is less than the significance level (denoted α, alpha). The p-value is the probability of obtaining at least as extreme results given that the null hypothesis is true whereas the significance level α is the probability of rejecting the null hypothesis given that it is true. Equivalently, when the null hypothesis specifies the value of a parameter, the data are said to be statistically significant at given confidence level γ = 1 − α when the computed confidence interval for that parameter fails to contain the value specified by the null hypothesis.
As a matter of good scientific practice, a significance level is chosen before data collection and is often set to 0.05 (5%). Other significance levels (e.g., 0.01) may be used, depending on the field of study. In any experiment or observation that involves drawing a sample from a population, there is always the possibility that an observed effect would have occurred due to sampling error alone. But if the p-value is less than the significance level (e.g., p < 0.05), then an investigator may conclude that the observed effect actually reflects the characteristics of the population rather than just sampling error. Investigators may then report that the result attains statistical significance, thereby rejecting the null hypothesis.
The present-day concept of statistical significance originated with Ronald Fisher when he developed statistical hypothesis testing based on p-values in the early 20th century. It was Jerzy Neyman and Egon Pearson who later recommended that the significance level be set ahead of time, prior to any data collection.
The term significance does not imply importance and the term statistical significance is not the same as research, theoretical, or practical significance. For example, the term clinical significance refers to the practical importance of a treatment effect.
Usage examples of "statistical significance".
Compared with what had been received from Vega, this could be at best a simple message, but its statistical significance was high.
Naturally, the statistical significance of the hypothesis of the role of the Penguins in the appearance of the phobia is indisputable.
There's nothing but a scattering without any statistical significance at all.
The statistical significance of the combined experiments departed from chance by a probability of one in a hundred billion!
Did the casualties have to reach statistical significance significance?
The association of warmer global temperatures with increasing carbon dioxide is good enough to pass tests of statistical significance.
Hard to find statistical significance there, because there's so much individual variation in how fast a dolphin learns a given task, but a lot of folks were surprised, in hindsight, that their animals weren't picking up tasks faster.