Usaldusnivoga

Usaldusnivoga, or confidence level, is a statistical concept that quantifies the degree of certainty a researcher has in the results of a statistical analysis, particularly when inferring conclusions about a population from a sample. It is most commonly associated with confidence intervals.

A confidence level, typically expressed as a percentage (e.g., 95%), indicates the probability that a calculated confidence interval contains the true population parameter. For instance, a 95% confidence level means that if the same sampling procedure were repeated many times, 95% of the resulting confidence intervals would capture the true population parameter.

It is crucial to understand that the confidence level does not refer to the probability that a specific, already computed interval contains the true parameter. Once an interval is calculated, the true parameter is either within it or not. The confidence level relates to the reliability of the method used to construct the interval over many repetitions.

Choosing a confidence level involves a trade-off. Higher confidence levels (e.g., 99%) provide greater certainty but result in wider intervals, offering less precision about the parameter's exact value. Conversely, lower confidence levels (e.g., 90%) yield narrower intervals, providing more precision but with less assurance that the interval captures the true parameter. Common confidence levels are 90%, 95%, and 99%.