on.
 <p>
 Specifically, the returned value is the smallest <code>alpha</code>
 such that the slope confidence interval with significance level
 equal to <code>alpha</code> does not include <code>0</code>.
 On regression output, this is often denoted <code>Prob(|t| > 0)</code>
 </p><p>
 <strong>Usage Note</strong>:<br>
 The validity of this statistic depends on the assumption that the
 observations included in the model are drawn from a
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