Gradient Boosting algorithms tackle one of the biggest problems in Machine Learning: bias. Decision Trees is a simple and flexible algorithm. An underfit Decision Tree has low depth, meaning it splits the dataset only a few of times in an attempt to separate the data. Because it doesn't separate the dataset into more and more distinct observations, it can't capture the true patterns in it. When it comes to tree-based algorithms Random Forests was revolutionary, because it used Bagging to reduce the overall variance of the model with an ensemble of random trees.
Two-Class Boosted Decision Tree module creates a machine learning model that is based on the boosted decision trees algorithm. A boosted decision tree is an ensemble learning method in which the second tree corrects for the errors of the first tree, the third tree corrects for the errors of the first and second trees, and so forth. Predictions are based on the entire ensemble of trees together that makes the prediction. Step 1 Add the Boosted Decision Tree module to the experiment. Step 2 Specify how you want the model to be trained, by setting the Create trainer mode option.
In this post, I am going to compare two popular ensemble methods, Random Forests (RM) and Gradient Boosting Machine (GBM). GBM and RF both are ensemble learning methods and predict (regression or classification) by combining the outputs from individual trees (we assume tree-based GBM or GBT). They have all the strengths and weaknesses of the ensemble methods mentioned in my previous post. So, here we compare them only with respect to each other. GBM and RF differ in the way the trees are built: the order and the way the results are combined.
The Kaggle competitions are like formula racing for data science. Winners edge out competitors at the fourth decimal place and like Formula 1 race cars, not many of us would mistake them for daily drivers. The amount of time devoted and the sometimes extreme techniques wouldn't be appropriate in a data science production environment, but like paddle shifters and exotic suspensions, some of those improvement find their way into day-to-day life. Ensembles, or teams of predictive models working together, have been the core strategy for winning at Kaggle. They've been around for a long time but they are getting better.
TF Boosted Trees (TFBT) is a new open-sourced frame-work for the distributed training of gradient boosted trees. It is based on TensorFlow, and its distinguishing features include a novel architecture, automatic loss differentiation, layer-by-layer boosting that results in smaller ensembles and faster prediction, principled multi-class handling, and a number of regularization techniques to prevent overfitting.