AST for Software Metrics Halstead's "software physics"(introduced in 1977) n1/n2:distinct operator/operand N1/N2:occurrences of operator/operand program length N N1+N2 program volume V Nl0g2(n1+n2) ■specification abstraction level L=2n2/(n1·N2） ■program effort E=(n1+N2·N.log2(n1+n2)/2m2 We can mine correlations between software metrics and quality/maintainability/...AST for Software Metrics : distinct operator/operand : occurrences of operator/operand program length program volume specification abstraction level program effort … We can mine correlations between software metrics and quality/maintainability/… Halstead’s "software physics" (introduced in 1977) n1/n2 N1/N2 N = N1 + N2 V = N log2(n1 + n2) L = 2n2/(n1 ⋅ N2) E = (n1 + N2 ⋅ N ⋅ log2(n1 + n2))/2n2