This page looks-up critical t-score values from the t score table to facilitate decisions about statistical significance.

Select the number of tails.

Select the desired p value.

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Explanation

Statistical significance is a way of saying that the null hypothesis is unlikely to be true. These situations have probabilities that will be in the tails of the t-distribution. So where does the tail part begin? The critical value defines where statistical significance would begin.

For one-tailed tests (for a prediction of higher scores):

For two-tailed tests:

Obtained t-test scores that are more extreme than the t_{critical} value are statistically significant. If your calculated t score (t_{obtained}) goes beyond t_{critical}, then p < .05 and the null hypothesis is rejected. In other words, your t score is out in the tail region and unlikely to occur by chance. Otherwise, when t_{obtained} is less t_{critical} the p value is p > .05 and the null hypothesis is kept. These outcomes are in the middle (near t = 0) and are likely to occur by chance.