And in most cases, your cutoff for rejecting the null hypothesis will be 0.05 – that is, when there is a less than 5% chance that you would see these results if the null hypothesis were true. In most cases you will use the p-value generated by your statistical test to guide your decision. This value is the p-value for a one-tailed test. When the calculated value of the test statistic from the sample is negative, calculate a lower-tailed p-value and in step 5 enter K2 in Optional storage.
Knowing how to compute the probability value using Excel is a great time-saver. Since the calculated value of the test statistic from the sample is positive, calculate an upper-tailed p-value. Its use in hypothesis testing is common in many fields like finance, physics, economics, psychology, and many others. Step 4: Decide whether to reject or fail to reject your null hypothesisīased on the outcome of your statistical test, you will have to decide whether to reject or fail to reject your null hypothesis. The p-value, short for probability value, is an important concept in statistical hypothesis testing. Your t-test shows an average height of 175.4 cm for men and an average height of 161.7 cm for women, with an estimate of the true difference ranging from 10.2cm to infinity. z test calculator will allow you to compute the critical values are p-values for.