5. Conclusion
This paper has proposed a novel fuzzy time-series model based on rough set rule induction for forecasting stock index, the proposed model utilized rough set LEM2 algorithm to generate forecast rules, it’s different from previous fuzzy time series using FLRs and employed adaptive expectation model to strengthen forecasting performance. The results have shown the proposed model with better forecast performance in accuracy and profit. From three stock markets data with 45 sub-datasets, we can conclude that there are four findings as follows.
(1) The number of linguistic interval Table 7 show that the nine linguistic intervals will result in the higher forecasting performance. From Yu [36], the more linguistic intervals utilize the more get forecast performance. However, based on Miller [10], the appropriate number of category for human shorten memory function is seven, or seven plus or minus two. That is, many linguistic intervals would disturb human shorten memory function for investors. Therefore, this study suggests that nine linguistic intervals with rule filter is a good approach.
(2) Whether rule filtered After filtering the generated rules (remove the “support” less than 2), the higher support rules can get the better forecasting performance as Table 7. i.e., the higher support rules in the training data have higher data matching, and then the forecast performance of proposed model will be better for testing data.