A forecast based only on earlier values of a time series or on observations taken from a similar set of <a href="search.pl?p=cross-sectional data">cross-sectional data</a>. Principles for extrapolation are described in Armstrong (2001c). <o:p></o:p></P>
<ul>
  <li>Armstrong, J. S. (2001c), “Extrapolation for time-series 
and cross-sectional data,” in J. S. Armstrong (ed.), <I>Principles of 
Forecasting</I>. Norwell, MA: Kluwer Academic Press.</li>
</ul>