A characteristic of time-series models (the I in <a href="search.pl?p=ARIMA">ARIMA</a> models) in which one or more of the differences of the <a href="search.pl?p=time-series data">time-series data</a> are included in the model. The term <I>integrated</I> is used because the original series may be recreated from a differenced series by summation.<o:p></o:p></P>