Critical Value Calculator

This gives the critical value for a hypothesis test: the cut-off the test statistic has to pass before the null hypothesis is rejected. Pick the standard normal, Student t, chi-square or F distribution, enter the significance level and the degrees of freedom the test uses, and choose one tail or two; the result is the cut-off to six decimals along with the area in each tail, the matching confidence level and the rejection rule in words. Nothing is read off a stored table, so any alpha between 0.0001 and 0.5 works rather than only the printed columns. The chi-square and F arms can also return both bounds at once, which is what a variance interval needs.