The weight reference period was moved to 1999. Enterprises were selected that had a significant share in the domestic sales for 4-digit SKP groups. Care was taken to select enterprises of different size classes. Products were selected that had a significant share in domestic sales. The representative items should have constant technical and utilitarian characteristics and should be sold, if possible, under the same trade supply and payment conditions.
Same products reported by different enterprises each have their own, specific weights.
Modified Laspeyres formula with fixed base. Individual price indices of representative items are aggregated into groups, subcategories, categories, and totals by computing weighted arithmetic averages. No adjustments were made to align the weight and the price reference periods. Occasionally, the price for a missing item is carried one month forward. Longer periods of missing prices require replacement of the item or the reporting unit.