Ancillary revenues play a big role in boosting total revenues for low-cost airlines in Europe. A study looked at data from three airlines between 2006 and 2011 and found that these extra revenues have a significant impact on the overall profit or loss of the airlines. In many cases, ancillary revenues made up a double-digit percentage of the total revenue changes. This shows that these extra revenues are a key factor in how much money the airlines make. The study used a quantitative approach to show that ancillary revenues are a major driver of profits for low-cost airlines.