Data withheld from a series that are not used in estimating <a href="search.pl?p=parameters">parameters</a>. These holdout data can then be used to compare alternative models. See <a href="search.pl?p=post-sample evaluation">post-sample evaluation</a> and <a href="search.pl?p=ex ante forecast">ex ante forecast</a>. For a discussion of the types of holdout data, see Armstrong (2001d).<o:p></o:p></P>
<ul>
  <li>Armstrong, J. S. (2001d), “Evaluating forecasting 
methods,” in J. S. Armstrong (ed.), <I>Principles of Forecasting.</I> Norwell, 
MA: Kluwer Academic Press.</li>
</ul>