# Find an F-based P-value

Find an F-based P-value##
Minitab^{®}
– Procedure

You may need to find a *P*-value if you are using the *P*-value approach to conduct a hypothesis test that uses an *F*-statistic.

- Select
**Calc**>>**Probability Distributions**>>**F**... - Click the button labeled
**Cumulative probability**. (Leave the non centrality parameter set as the default of 0.) - Type the number of numerator degrees of freedom in the box labeled
**Numerator d****egrees of freedom**, and type the number of the denominator degrees of freedom in the box labeled**Denominator degrees of freedom**. - Click the button labeled
**Input constant**. In the box, type the value of your*F*-statistic for which you want to find the associated cumulative probability. - Select
**OK**. The cumulative probability will appear in the session window. The*P*-value is 1 minus the reported cumulative probability.

##
Example

The coolhearts.txt data set contains the following data on 32 rabbits subjected to a heart attack:

*y*_{i}is the size of the infarcted area (in grams) of rabbit*i**x*_{i1}is the size of the region at risk (in grams) of rabbit*i**x*_{i2}= 1 if early cooling of rabbit*i*, 0 if not*x*_{i3}= 1 if late cooling of rabbit*i*, 0 if not

It can be shown that the partial *F*-statistic for testing *H*_{0} : *β*_{2} = *β*_{3} = 0 is 8.59 with 2 numerator and 28 denominator degrees of freedom. Find the *F*-based *P*-value so that you can draw a conclusion about the hypothesis.

## Minitab Dialog Box

### Sample Minitab Output

### Cumulative Distribution Function

F distribution with 1 DF in numerator and 28 DF in denominator

x | P ( X ≤ x) |
---|---|

8.59 | 0.998767 |

The *P*-value is therefore 1 - 0.9988 or 0.0012.