This study looked at rental markets in France by using data from online ads to understand how rents vary across different areas. By analyzing this data, researchers found that rents in tight housing markets don't increase as much as prices do. They were able to estimate the market rent for each transaction and for social dwellings, showing how much benefit social tenants receive based on rental prices in their area. The online ads provided unbiased information about rental markets and allowed coverage of the entire country, giving a more complete picture than other sources.