Because inverse distance weighting is a deterministic technique, it does not take into account the spatial structure (i.e., arrangement) of the sample points. Therefore, the results that you get using this technique can be influenced by the spacing and density of the samples, and it is good to be cautious about the accuracy of the interpolated values. Also, because inverse distance weighting computes an average value, the value it calculates for a non-sampled point can never be higher than the maximum value for a sample point or lower than the minimum value of the sample point, so if the peaks and valleys of the data are not represented in your sample, this technique may be wildly inaccurate in some locations.