A term used to denote a time series of non-negative integer values where some values are zero. For example, shipments to a store may be zero in some periods because a store’s inventory is too large. In this case, the demand is not zero, but it would appear to be so from the data. Croston’s method (Croston 1972) was proposed for this situation. It contains an error that was corrected by Rao (1973). Willemain et al. (1994) provide evidence favorable to Croston’s method. Other procedures such as aggregating over time can also be used to solve the problem. See Armstrong (2001c). <o:p></o:p></P>
 <ul>
   <li>Croston, J. D. (1972), “Forecasting and stock control 
for intermittent demand,” <I>Operational Research Quarterly</I>, 23, 
289-303.<B><o:p></o:p></B></SPAN></li>
   <li><SPAN Plous, 
S. (1993), <I>Rao, A. V. (1973), “A comment on forecasting and stock 
control for intermittent demands,” <I>Operational Research Quarterly</I>, 24, 
639-640.</SPAN></li>
   <li>Willemain, T. R., C. N. Smart, J. H. Schockor &amp; P. 
A. DeSautels (1994), “Forecasting intermittent demand in manufacturing: A 
comparative evaluation of Croston’s method,” <I>International Journal of 
Forecasting</I>, 10, 529-538.</li>
   <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>