**Inverse distance weighting** is a type of deterministic method for [[Spatial Interpolation|spatial interpolation]], even though it also can be used to create spatial weight matrices in [[Spatial Autocorrelation|spatial autocorrelation]] methods like [[Moran's I]]. It is traditionally defined as $u(x)$, where: $ u(x) = \frac{ \sum^{N}_{i=1} w_i(x) u_i } { \sum^{N}_{i=1} w_i(x) } $ Where $x$ is an arbitrary point (to interpolate), $x_i$ is a known point (whose value is $u_i$) and $w_i(x)$ is the weight function to the point $x_i$ defined as: $ w_i(x) = \frac{1}{d(x, x_i)^p} $ Where $d$ is the [[Distance Function|distance function]] and $p$ is a positive real number known as the power parameter.