There are many other instances, of course, when older information is inaccurate. Check the date of the material you are using. Statistical tables should indicate on the table the date of the information given. Tables usually give the name of the group or agency that compiled them. It's worth checking to see if later figures are available.
Office holders change very fast.
Directories are generally out of date before they are published. Check with your patron to find out if newer material is needed. If it is, offer to pursue the question, giving the patron a realistic idea of when you might have updated material. Or, if a person is looking for the name of a current office holder, offer to supply the phone number of the government office. Give the patron the most current information.