Signifikansnivået

Signifikansnivået, often denoted by the Greek letter alpha (α), is a fundamental concept in statistical hypothesis testing. It represents the probability of making a Type I error, which is rejecting a true null hypothesis. In simpler terms, it's the threshold below which a result is considered statistically significant.

When conducting a hypothesis test, researchers set a significance level before analyzing the data. Common choices for α are 0.05 (or 5%), 0.01 (or 1%), and 0.10 (or 10%). A significance level of 0.05 means that there is a 5% chance of concluding that a difference or effect exists when, in reality, there is none.

The p-value obtained from a statistical test is then compared to the chosen significance level. If the p-value is less than or equal to the significance level (p ≤ α), the null hypothesis is rejected, and the result is deemed statistically significant. Conversely, if the p-value is greater than the significance level (p > α), the null hypothesis is not rejected, and the result is not considered statistically significant at that chosen level.

The choice of significance level depends on the context of the research and the consequences of making a Type I error. A lower significance level reduces the risk of a Type I error but increases the risk of a Type II error (failing to reject a false null hypothesis). Therefore, researchers must carefully consider the trade-offs when selecting their α value.