A method of processing geological data is provided for input to a geostatistical modelling algorithm to predict a value for a parameter relating to a physical property of the Earth. An input data set corresponding to a measured geological parameter is processed to determine a characteristic function of the input data with respect to a geological measure. The input data is transformed to reduce spatial bias with respect to the geological distance measure by applying an inverse function. A statistical weighting is calculated for the transformation and the transformation and weighting are used to predict a representative value of the physical property corresponding to the measured geological parameter. A data processing apparatus and computer program product are also provided.