Slower Can Be Faster: The iRetis Incremental Model Tree Learner.

Incremental learning is useful for processing streaming data, where data elements are produced at a high rate and cannot be stored. An incremental learner typically updates its model with each new instance that arrives. To avoid skipped instances, the model update must finish before the next element arrives, so it should be fast. However, there can be a trade-off between the efficiency of the update and how many updates are needed to get a good model. We investigate this trade-off in the context of model trees. We compare FIMT, a state-of-the-art incremental model tree learner developed for streaming data, with two alternative methods that use a more expensive update method. We find that for data with relatively low (but still realistic) dimensionality, the most expensive method often yields the best learning curve: the system converges faster to a smaller and more accurate model tree.