Level of confidence:

A percentage or decimal value that tells how confident a researcher can be about being correct. It states that the long run percentage of the time that a confidence interval will include the true population mean. Alternatively, it is the probability of not rejecting the null hypothesis when it is true, equal to 1– α. Confidence level is used in sample size selection. There is inverse relationship between sample size and the level of confidence. Traditionally, researchers have used 95% confidence level. It is also referred to as level of significance.