Considered methods

• closest observation method

  \(\hat{Z}(s_0) = Z(s_{closest})\)

• inverse distance weighting method (IDW)

  \(\hat{Z}(s_0) = \sum_{i = 1}^{n}(Z(s_i) \cdot w_i)\)

  • with \(w_i = d_i^{-\beta} / \sum_{i = 1}^{n}d_i^{-\beta}\)
  • optionally replace \(n\) by \(k < n\): use only the \(k\) nearest locations