tail (integral) from z up to
            +&#8734;, and a two-sided test where we are using two &gt; <span class="bold"><strong>and</strong></span>
            &lt; tests, and thus considering two tails, from -&#8734; up to z low and z high
            up to +&#8734;.
          </p>
<p>
            So the 2-sided values alpha[i] are calculated using alpha[i]/2.
          </p>
<p>
            If we consider a simple example of alpha = 0.05, then for a two-sided
            test, the lower tail area from -&#87