to:rubenfcasal@gmail.com" class="email">rubenfcasal@gmail.com</a>.</p>
</div>
<div class="section level2">
<h2 id="acknowledgments">Acknowledgments<a class="anchor" aria-label="anchor" href="#acknowledgments"></a>
</h2>
<p>Important suggestions and contributions to some techniques included here were made by Sergio Castillo-Páez (Universidad de las Fuerzas Armadas ESPE, Ecuador) and Tomas Cotos-Yañez (Dep. Statistics, University of Vigo, Spain).</p>
<p>This research has been supported by MINECO grant MTM20