Is the slope significantly different than zero?

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Prism reports the P value testing the null hypothesis that the overall slope is zero. The P value answers this question:

If there were no linear relationship between X and Y overall, what is the probability that randomly selected points would result in a regression line as far from horizontal (or further) than you observed?

Equivalently:

If there were no linear relationship between X and Y overall, what is the probability that randomly selected points would result in an R2 value as high (or further) as you observed?

The P value is calculated from an F test, and Prism also reports the value of F and its degrees of freedom. You would get exactly the same P value from the t ratio computed by dividing the slope by its standard error.


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