Collected prices - about 3 to 5,000 price in each French overseas department, 9,000 in Corsica and 9,000 in metropolitan France (in addition to the price index Consumption - CPI) - were carried out in different outlets. In addition to this field collection, some prices were collected centrally like electricity, communication services, health or different public services.

Punctual or aperiodic

The prices were collected by the network of INSEE price collectors throughout from February to April 2015.

In metropolitan France, consumer price index (CPI) data were used and complementary surveys were carried out on the one hand for the typical products of the French overseas departments which are not usually surveyed in Metropolitan France for CPI purpose, and on the other hand for the products that are too heterogeneous to use CPI prices.
In the oversea territories, the complementary survey was mainly used, with the prices taken from the CPI collection limited to foodstuffs.
In Corsica, only the complementary survey  was used.

The survey is conducted on the Metropolitan territory (including Corsica) and the five overseas departments : Guadeloupe, Martinique, French Guyana, Reunion Island and Mayotte. The surveys are carried out in 12 agglomerations  with more than 2,000 inhabitants spread over the continental metropolitan territory and belonging to different size classes, as well as in 4 agglomerations in Corsica and a dozen for the overseas departments.

Prices are recorded to the cent.
The collected prices are the prices, excluding sales and promotions.

Data collection frequency: five-yearly.
Frequency of dissemination: five years (5-year rhythm).

Price collection was conducted from February to April 2015.

All types of sales outlets were surveyed, according to their local representativeness. Between 3,000 and 5,000 price readings were taken in each of the overseas departments.

In Corsica, the number was raised to around 9,000, because it was necessary to add the field of food products as well as certain products not included in the comparison with the DOM, as they were absent or barely representative on these territories.

For mainland France, the number of collected prices was around 9,000, i.e. approximately a hundred products and around 50 prices per product, spread across 15 conurbations in provincial France and in the Parisian conurbation. In addition to these prices collected in purpose, prices from CPI were used. Finally, 90,000 prices collected in mainland France were used for the spatial comparison.

As for the CPI, the sample is stratified according to three types of criteria:
- a geographical criterion: the surveys are carried out in 15 agglomerations with more than 2,000 inhabitants spread over mainland continental territory and belonging to different size classes in addition to the Parisian conurbation, as well as in 4 agglomerations in Corsica and more than 15 units for all overseas departments;
- a product type criterion: a sample of 400 product families (consumption segments) consumed in both metropolitan France and overseas departments is defined;
- a point of sale type criterion: a stratification by form of sale (hypermarkets, etc.) is constituted to represent the diversity of the products and modes of purchase of the consumers.

Data are validated at different level of the statistical process: collection of the data, sample design, methodology…

The national weights of the COICOP items are determined on the basis of the data derived from the National Accounts. Regional weights were computed thanks to the household budget survey.