For each compound, only the data of the highest dose group and its control group was used. Of 150 compounds, we omitted one compound and analyzed the remaining 149 compounds because that one compound was found to have killed animals before
15D in the study and therefore no data is available for 3-Methyladenine liver weight of 15D. In courtesy of Dr. Frans Coenen, we used a CBA program available on the LUCS-KDD website, which is implemented according to the original algorithm by , except that CARs are first generated using the Apriori-TFP algorithm instead of the CBA-RG algorithm. The basic concept of CBA is briefly explained here based on the explanations from  with examples in this study. For detail, refer to . Let D be the dataset, a set of records
d (d ∈ D). Let I be the set of all non-class items in D, and Y be the set of class labels in D. In this study, a non-class item is a pair of gene ID and its discretized expression (Inc or Dec) (Inc: Increased, Dec: Decreased) and a class label is a pair of a target parameter (RLW: relative liver weight) and its discretized value (Inc or NI, or Dec or ND) (NI: Not Increased, ND: Not Decreased). The set of class labels Y in this study is either (RLW, Inc), (RLW, NI) or (RLW, Dec), (RLW, ND). We say that Sotrastaurin molecular weight a record d ∈ D contains X ⊆ I, or simply X ⊆ d, if d has all the non-class items of X. Similarly, a record d ∈ D contains y ∈ Y, or simply y ⊆ d, if d has the class label y. A rule is an association of the form X → y (e.g. (Gene_01, Inc), (Gene_02, Dec) → (RLW, Inc)). For a rule X → y, X is called an antecedent of the rule and y is called a consequence of the rule. A rule X → y holds in D with confidence c if c% of the records in D
that contain X are labeled with class y. A rule X → y has support s in D if s% of the records in D contain X and are labeled with class y. The objectives of CBA are (1) to generate the complete set of rules that satisfy the user-specified minimum support (called minsup) and minimum confidence (called minconf) Nutlin 3 constraints, and (2) to build a classifier from these rules (class association rules, or CARs). The original CBA algorithm of Liu et al. consists of two parts, a rule generator (called CBA-RG) and a classifier builder (called CBA-CB), each corresponding to (1) and (2). The key operation of CBA-RG is to find all rules X → y that have support above minsup. Rules that satisfy minsup are called frequent, while the rest are called infrequent. For all the rulesthat have the same antecedent, the rule with the highest confidence is chosen as the possible rule (PR) representing this set of rules. If there are more than one rules with the same highest confidence, one rule is randomly selected. If the confidence is greater than minconf, the rule is accurate.