The policy of the National Travel and Tourism Office (NTTO) is to release visitation estimates only for those destinations in which a sample of 400 or more respondents was collected from the Survey of International Air Travelers (SIAT), based upon a single year's interviews. A random sample of 400 respondents (rounded) would yield a 95 percent confidence level with a plus or minus 5 percentage point variance. The NTTO's survey methodology is not a random sample but, is based upon a stratified, two-stage cluster sample. The NTTO statistical policy was implemented to raise the level of confidence in the survey estimates and takes into account input from the National Council of State Travel Directors, State Researchers Group, and other industry clients.
The NTTO statistical policy on the release of visitation volume estimates for countries, census and tourism regions, states, and cities, requires that more than 400 travelers were surveyed for each volume estimate.
The NTTO recognizes that providing visitation estimates is the most valuable piece of information it releases and that it is the only source for the majority of the international travel data available for the United States. The impact of its estimates is not only felt at the national level, but throughout the world. This statistical policy was implemented for inbound travelers to the United States, outbound travel, and the Canadian and Mexican visitation estimates. The policy was implemented to enlist an enhanced level of the cooperation from the travel and tourism industry to further improve the programs implemented by the NTTO. By working together, all parties will obtain better information on the international travel market to and from the United States.
This policy is reviewed annually under the guidance of the NTTO staff and in consultation with travel and tourism industry stakeholders. The NTTO’s international visitation data public release is available through its website,