## 29.5$$P$$-values: Consistency with assumption?

A $$P$$-value determines if the sample data are consistent with the assumption (Table 28.1), Since $$t=1.681$$, the one-tailed $$P$$-value is between 2.5% and 16% based on the 68–95–99.7 rule. This is a wide, and inconclusive, interval. Software gives a more precise $$P$$-value (jamovi: Fig. 29.4; SPSS: Fig. 29.5): the two-tailed $$P$$-value is $$0.127$$, so the one-tailed $$P$$-value is $$0.127/2 = 0.0635$$.

The software clarifies how the differences have been computed:

• jamovi: At the left of the output (Fig. 29.4), the order implies the differences are found as Before minus After.

• SPSS: At the left of the output (Fig. 29.5), the difference is described as Before $${}-{}$$ After.

Click on the hotspots in the following image, to see how to read the SPSS output.