Generally, as listed, the validity and reliability of any particular web site would tend to decline depending on what type of site it is. That is, sites associated with known research programs in major universities or related settings would tend to be the best sources of information while those that represent agencies with political agendas or individuals who are pushing a certain agenda are the least reliable. Similarly, information found in research journals sponsored by professional associations such as the American Sociological Association or the American Political Science Association tends to be stronger than information found in journalistic sources. Information in research sources is submitted for review and is refereed or peer reviewed by other professionals in the field prior to publication. Many journalistic sources tend to emphasize currency and speed with accuracy tending to follow.
All state governments have similar data-generating programs.
Also, the United Nations has an extensive set of databases that support its programs. Many governments around the world also have good web sites and databases from which to draw data. However, as the government becomes less democratic, its database becomes more suspect as political agendas begin to intrude. The resources available to support the research may also compromise the information. The comparability of the information across societies is also an issue.