Service Analytics

8.Anomaly Detection

Grid-based subspace outlier detection

Algorithm
  • Find the m grid cells (projections) with the lowest sparsity coefficients
  • Brute-force algorithm is in O(Φd)
  • Evolutionary algorithm (input: m and the dimensionality of the cells)

Discussion

  • Very coarse model (all objects that are in cell with less points than to be expected)
  • Quality depends on grid resolution and grid position
  • Implements a global approach (key criterion: globally expected number of points within a cell)

Diskussion