Global projects sometimes run into the "shifting goal posts" problem. They are carefully designed to meet one set of objectives but when the project is set up, or, worse still, when the results are reported, it is discovered that the real objectives are somewhat different. Consultation with key stakeholders is critical before the project is implemented.
No matter how well-informed and well-intentioned it is impossible to appreciate all the local needs and issues from the company headquarters, whether it is in New York, London or Beijing. Make sure that key stakeholders are involved before issuing the project brief.
Distance breeds confusion and distrust. Good communication and a consultative approach will go a long way to ameliorating local concerns about the value of the project.
In many cases local markets may have been using a different methodology for years. Disrupting the established database and norms can be a huge problem. Consider duplicating the work in order to provide a "bridge" but do not try to adjust the new data to be consistent with the old: it rarely satisfies anyone and simply adds cost.
You cannot get global service for a local price. There are a lot of overheads to the effective implementation of a global research project that are not incurred with a project conducted in a single market. Regional coordination, translation and travel costs are additional to the equivalent national study and often overlooked.