Of course, you don’t have to clean your own data. A number of service bureaus, data providers, and such will scrub your data to various degrees of cleanliness. Some of these companies don’t do anything you can’t do yourself—although they’re likely to do a better job because they’re more experienced. However, others have the resources to do a much better job of data cleaning than most organizations can. For example, a number of data provision companies, such as Experian, offer services to check names and addresses and some other information against their databases. Usually this service can be performed online in batches, or against a CD-ROM of the relevant data. Since companies like Experian and Harte-Hanks regularly check public records databases, they’re especially good at weeding out customers who have died or moved.
Data cleaning by information providers is expensive, and the companies are geared to handle tens or hundreds of thousands of records, preferably on an ongoing basis. Many of the service bureaus are set up to handle smaller quantities of data on a one-time basis, though.