Indexreeksen

Indexreeksen (Dutch for “index series”) are sequences of numbers that express the relative change of a variable over time. They are widely used in economics, statistics and finance to compare values across periods without relying on absolute levels. An index typically uses a base period in which the index value is set to a fixed number, usually 100, and subsequent values indicate how much the variable has risen or fallen relative to that base.

Indexreeksen can be constructed with different base methods. In a fixed-base index, all values reference the same base period. In a chained index, the base period can shift as new data become available. Common calculation methods include Laspeyres, Paasche, and the Fisher index, which differ in how weights are defined for the components of the basket.

Indexreeksen may measure prices, quantities, or other indicators. Price indices such as the consumer price index (CPI), producer price index, or a market index in finance are typical examples. GDP deflator is another widely used index that combines price and quantity changes.

Advantages of indexreeksen include the ability to track relative changes over time and to deflate nominal values for real comparison. Limitations include sensitivity to changes in composition, quality adjustments, and the choice of base period, which can affect interpretation, especially in the short term.

Overall, indexreeksen provide a compact, interpretable way to monitor trends and compare performance across time, regions, or sectors.