# How do I get my p-value?

## How do I get my p-value?

If your test statistic is positive, first find the probability that Z is greater than your test statistic (look up your test statistic on the Z-table, find its corresponding probability, and subtract it from one). Then double this result to get the p-value.

Why is p-value needed?

The p-value is used as an alternative to rejection points to provide the smallest level of significance at which the null hypothesis would be rejected. A smaller p-value means that there is stronger evidence in favor of the alternative hypothesis.

### Do you want p-value to be high or low?

The smaller the p-value, the stronger the evidence that you should reject the null hypothesis. A p-value less than 0.05 (typically ≤ 0.05) is statistically significant. It indicates strong evidence against the null hypothesis, as there is less than a 5% probability the null is correct (and the results are random).

How do you calculate the p value?

The p-value is calculated using the sampling distribution of the test statistic under the null hypothesis, the sample data, and the type of test being done (lower-tailed test, upper-tailed test, or two-sided test).

#### How to find p value on calculator?

Left-tailed t-test: p-value = cdf t,d (t score)

• Right-tailed t-test: p-value = 1 – cdf t,d (t score)
• Two-tailed t-test: p-value = 2*cdf t,d (−|t score|) or p-value = 2 – 2*cdf t,d (|t score|)
• What is a p value and what does it mean?

The p-value is a number between 0 and 1 and interpreted in the following way: A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis, so you reject the null hypothesis. A large p-value (> 0.05) indicates weak evidence against the null hypothesis, so you fail to reject the null hypothesis.

## How to calculate p value?

– For a lower-tailed test, the p-value is equal to this probability; p-value = cdf (ts). – For an upper-tailed test, the p-value is equal to one minus this probability; p-value = 1 – cdf (ts). – For a two-sided test, the p-value is equal to two times the p-value for the lower-tailed p-value if the value of the test statistic from your sample is negative.