The idea of exploring fuzzy set theory to time series forecasting issues has been enormously
attracted researcher’s attention in recent years. Several new approaches on fuzzy time series have been
put forward. These approaches have got some advantages related to classical methods and are
complementary of them. Two of these kinds of procedures are FARIMA and FSARIMA. FARIMA and
FSARIMA do not require a restriction of at least 50 observations and linearity assumption. The
methods of FARIMA and FSARIMA provide interval estimates of a time series. ARIMA and SARIMA
also provide interval estimation but it has been put forward that estimated intervals are large, therefore
not informative. The width of estimated intervals obtained from FARIMA and SARIMA may generally
tend to be less than ones from ARIMA and SARIMA. In the literature, there has been no study which
provides a criterion for the comparisons of time series with respect to interval estimates. In this study,
two criteria for such comparisons are presented.
Keywords: ARIMA, Fuzzy ARIMA, Fuzzy SARIMA, Interval estimates, SARIMA.
