5097L-AU ABSTRACT The provision of, or generation of, a digitally encoded electric signal which represents an asset class capital gain index is disclosed. The asset class can include motor vehicles, or real estate. In respect of real estate rents or inputted rents can be included to enable rental yields to be ascertained. Historical sales data is manipulated to create adjusted price data representing all transactions as if they occurred on the same base date. This data is then transformed by a transform function (having an inverse) to create a transformed data set. The transformed data set is fitted via a generalized additive model to create a valuation function which is applied to the assets and the inverse taken to create a current value estimate for all assets, which is summed to created an index. 3/* 65CAMERA PRINTER 81 76 646 VIDEO E/O HDD FDD01 1 62 INTERFACE INTERFACE STORAGE DEVICE 64 REAR KEYBOARD 562 63 FI 72 63 FIG. 3