Page 103 - Demo

%u062c%u0645%u064a%u0639 %u0627%u0644%u062d%u0642%u0648%u0642 %u0645%u062d%u0641%u0648%u0638%u0629 %u0640 %u0627%u0625%u0644%u0639%u062a%u062f%u0627%u0621 %u0639%u0649%u0644 %u062d%u0642 %u0627%u0645%u0644%u0624%u0644%u0641 %u0628%u0627%u0644%u0646%u0633%u062e %u0623%u0648 %u0627%u0644%u0637%u0628%u0627%u0639%u0629 %u064a%u0639%u0631%u0636 %u0641%u0627%u0639%u0644%u0647 %u0644%u0644%u0645%u0633%u0627%u0626%u0644%u0629 %u0627%u0644%u0642%u0627%u0646%u0648%u0646%u064a%u0629103Na%u00efve Bayesian prediction requires each conditional probability be nonzero. Otherwise, the predicted probability will be zero. nP(X | Ci) = P(xk | Ci) k = 1Example: Suppose a dataset with 1000 tuples, income=low (0), income= medium (990), and income = high (10) Use Laplacian correction (or Laplacian estimator) Adding 1 to each case Prob(income = low) = 1/1003 Prob(income = medium) = 991/1003 Prob(income = high) = 11/1003 The %u201ccorrected%u201d prob. estimates are close to their %u201cuncorrected%u201d counterparts Advantages of Na%u00efve Bayes classifier that it is easy to implement , good results obtained in most of the cases . disadvantages are class conditional independence, therefore loss of accuracy. Practically, dependencies exist among variables E.g., hospitals: patients: Profile: age, family history, etc.Symptoms: fever, cough etc., Disease: lung cancer, diabetes, etc. Dependencies among these cannot be modeled by Na%u00efve Bayes Classifier IV. Rule-Based Classification Using IF-THEN Rules for Classification: Rules are a good way of representing information or bits of knowledge. A rulebased classifier uses a set of IF-THEN rules for classification. An IF-THEN rule is an expression of the form %u2018%u2019IF condition THEN conclusion.%u2019%u2019 An example is rule R1, R1: IF age = youth AND student = yes THEN buys computer = yes. The %u201cIF%u201d part (or left side) of a rule is known as the rule antecedent or precondition. The %u201cTHEN%u201d part (or right side) is the rule consequent. In the rule antecedent, the condition consists of one or more attribute tests (e.g., age = youth and student = yes) that are logically ANDed. The