4.53. The most common and rigorous method of observing expenditure by non‑resident visitors entails surveying them as they leave the country (see chapt. III, sect. C.2.2.1). The methods given below are used to observe inbound tourism expenditure. Further, it should be noted that the following discussions on border surveys, surveys at accommodation or tourism sites, and the use of electronic prints encompass elements of relevance to the measurement of domestic and outbound tourism expenditure as well.