Hypothesis Testing Calculator
Perform a complete hypothesis test step by step.
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Enter the sample mean, hypothesized population mean, standard deviation, sample size, and significance level. The calculator performs a two-tailed t-test and gives you the test statistic, p-value, and a clear reject/fail-to-reject decision.
About This Calculator
Hypothesis testing is the formal process of making statistical decisions. You start with a null hypothesis (H0, usually "no effect") and an alternative (H1). The test computes how unlikely your sample result would be under H0. If the p-value is less than alpha, you reject H0 in favor of H1.
Frequently Asked Questions
What does "fail to reject" mean?
It means the evidence is insufficient to reject the null hypothesis. It does not mean H0 is true, only that we cannot conclusively say it is false based on this data.
What is a Type I error?
A Type I error occurs when you reject a true null hypothesis (false positive). The significance level alpha is the maximum probability of a Type I error.
What is a Type II error?
A Type II error occurs when you fail to reject a false null hypothesis (false negative). The probability of avoiding this error is the statistical power.