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Fitting Models to Data

Fitting Models to Data. Linear and Quadratic Discriminant Analysis. Decision Trees. AID: Automatic Interaction Detector. Association Co- O ccurence. CHAID. CART: Classification and Regression Trees . CART family is oriented to statistics using the concept of impurity.

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Fitting Models to Data

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  1. Fitting Models to Data Linear and Quadratic Discriminant Analysis Decision Trees

  2. AID: Automatic Interaction Detector Association Co-Occurence

  3. CHAID

  4. CART: Classification and Regression Trees CART family is oriented to statistics using the concept of impurity Measures how well are the two classes separated – Ideally we would like toseparateall 0s and 1 http://freakonometrics.hypotheses.org/1279

  5. Fitting Models to Data

  6. OverFitting

  7. Bagging • Builds multiple decision trees by repeatedly resampling training data with replacement • Fit a Model to each Sample • Voting across the trees for a consensus prediction.

  8. Boosting • Learns slowly • Given the current model, we fit a decision tree to the residuals (misclassifications) from the model. • We then add this new decision tree into the fitted function in order to update the residuals. • Each of these trees can be rather small, with just a few terminal nodes, determined by the parameter d in the algorithm. • By fitting small trees to the residuals, we slowly improve fit in areas where it does not perform well

  9. Random Forests

  10. http://www.stat.berkeley.edu/~breiman/RandomForests/

  11. Gradient Boosting

  12. Many Algorithms Decision Trees Random Forests rpart (CART) tree (CART) ctree (conditional inference tree) CHAID (chi-squared automatic interaction detection) evtree (evolutionary algorithm) mvpart (multivariate CART) knnTree (nearest-neighbor-based trees) RWeka (J4.8, M50, LMT) LogicReg (Logic Regression) BayesTree TWIX (with extra splits) party (conditional inference trees, model-based trees) randomForest(CART-based random forests) randomSurvivalForest(for censored responses) party(conditional random forests) gbm(tree-based gradient boosting) mboost(model-based and tree-based gradient boosting)

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