In the fourth quarter of 2024, compared with the previous quarter, the producer price index in the services sector rose by 0.5%. Compared with the same quarter last year, it rose by 2.1%.

A further breakdown of services shows that :

• For land transport and transport via pipelines, the prices fell by 0.5% compared to the last quarter. Inflation stands at 1.2%.
• For warehousing and support activities for transportation, the prices rose by 0.6% compared to the last quarter. Inflation stands at 2.4%.
• For postal and courier activities, the prices rose by 0.2% compared to the last quarter. Inflation stands at 10%.
• For food and beverage service activities, the prices rose by 1% compared to the last quarter. Inflation stands at 4.6%.
• For computer programming, consultancy and related activities, the prices rose by 0.8% compared to the last quarter. Inflation stands at 5%.
• For information service activities, the prices rose by 0.1% compared to the last quarter. Inflation stands at 2%.
• For real estate activities, the prices rose by 0.4% compared to the last quarter. Inflation stands at -4.3%.
• For legal and accounting activities, the prices stabilized compared to the last quarter. Inflation stands at 2.8%.
• For activities of head offices; management consultancy activities, the prices rose by 1.6% compared to the last quarter. Inflation stands at 2.6%.
• For architectural and engineering activities; technical testing and analysis, the prices fell by 0.3% compared to the last quarter. Inflation stands at 2.4%.
• For employment activities, the prices rose by 1.3% compared to the last quarter. Inflation stands at 2.5%.

As part of the change of base year (2021 = 100), the methodology for the service price index has been revised. The major changes made are:

• the publication of additional NACE and at more detailed levels
• the creation of an intermediate classification of enterprises in the sample into strata
• the inclusion of new enterprises from year to year
• the control of chain drift
• the definition and application of a strategic outlier exclusion method adapted to the data at NACE level
• the imputation by the highest NACE level available

Attached to this press release is a note containing examples of how the old and new figures can be combined.

Addition of NACE Sectors

Following the revision of the sample, the different NACE levels and the data were analyzed to determine whether it was possible to publish at NACE 3 and NACE 4 levels. The publication will now be more detailed and comprehensive.

Enterprise strata

The enterprises in the sample are weighted according to their turnover. Before the revision, the weight was a ratio between the enterprise’s turnover and the sum of the turnovers for each NACE. The new method introduces an intermediate level. We create three strata: small, medium and large enterprises. The weights are then rebalanced, avoiding an over-representation of large sampled enterprises and an under-representation of small enterprises.

Inclusion of new enterprises

Firstly, we took advantage of the creation of the new indices to include prices that had been collected but not yet used. Secondly, in the new method we have added an annual review of the enterprises used, enabling us to allocate a weight to the new enterprises in the survey and to include their prices in the index from year to year. In this way, the representativeness of the sample can be guaranteed over time.

Control of chain drift

Chain drift can result from price variations, pulling the index up or down. When product prices return to their initial level without the index also returning to its base level, there is a chain drift. This effect is mathematically corrected in the new method.

Exclusion of outliers

Previously, outliers were only detected based on an abnormal quarter-to-quarter ratio or a change in description. In the new method, other cases are added, such as prices that have been stable for more than 6 quarters. This new strategy enables us to improve the quality of the data received via our survey. This change makes the indices more representative from quarter to quarter.

Imputation by higher NACE level

In the old method, when no price was available for a certain NACE, the evolution was imputed by 1 (constant). In the new method, the change from quarter to quarter is imputed by that of the higher NACE level available. This method makes it possible to take into account the differences in reality between the various activity sectors. For example, if we do not receive any prices for NACE 6201, we will use the evolution in NACE 620.