Classification Models Pros and Cons


Classification Model Pros and Cons (Generalized)

  • Logistic Regression
    • Pros
      • low variance
      • provides probabilities for outcomes
      • works well with diagonal (feature) decision boundaries
      • NOTE: logistic regression can also be used with kernel methods
    • Cons
      • high bias
  • Decision Trees
    • Regular (not bagged or boosted)
      • Pros
        • easy to interpret visually when the trees only contain several levels
        • Can easily handle qualitative (categorical) features
        • Works well with decision boundaries parellel to the feature axis
      • Cons
        • prone to overfitting
        • possible issues with diagonal decision boundaries
    • Bagged Trees : train multiple trees using bootstrapped data to reduce variance and prevent overfitting
      • Pros
        • reduces variance in comparison to regular decision trees
        • Can provide variable importance measures
          • classification: Gini index
          • regression: RSS
        • Can easily handle qualitative (categorical) features
        • Out of bag (OOB) estimates can be used for model validation
      • Cons
        • Not as easy to visually interpret
        • Does not reduce variance if the features are correlated
    • Boosted Trees : Similar to bagging, but learns sequentially and builds off previous trees
      • Pros
        • Somewhat more interpretable than bagged trees/random forest as the user can define the size of each tree resulting in a collection of stumps (1 level) which can be viewed as an additive model
        • Can easily handle qualitative (categorical) features
      • Cons
        • Unlike bagging and random forests, can overfit if number of trees is too large
  • Random Forest
    • Pros
      • Decorrelates trees (relative to bagged trees)
        • important when dealing with mulitple features which may be correlated
      • reduced variance (relative to regular trees)
    • Cons
      • Not as easy to visually interpret
  • SVM
    • Pros
      • Performs similarly to logistic regression when linear separation
      • Performs well with non-linear boundary depending on the kernel used
      • Handle high dimensional data well
    • Cons
      • Susceptible to overfitting/training issues depending on kernel
  • Neural Network (This section needs further information based on different types of NN’s)
  • Naive Bayes
    • Pros
      • Computationally fast
      • Simple to implement
      • Works well with high dimensions
    • Cons
      • Relies on independence assumption and will perform badly if this assumption is not met

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