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Guide to Researching US Tax Policy

A Method to Evaluate Sources


It is very important to critically examine any source you intend to use, but particularly important for those found on the Internet. Use the CAST method of evaluation: (1) Credibility, (2) Accuracy, (3) Scope, and (4) Time.

When examining credibility consider things like:

  • Who is the author/publisher?
  • What is the author’s education, training and experience?
  • If it is an organization, is the organization known and respected?
  • What is the organization’s purpose or mission?

When examining accuracy consider things like:

  • What is the source of the data and is it trustworthy?
  • Are the sources cited?  Are the sources trustworthy?
  • Can the data be corroborated or confirmed?
  • Are there obvious errors in the information?
  • Is the information factual in nature or opinion? On what are the opinions based?
  • Is the information of consistent quality?

When examining scope consider things like:

  • Are there political or ideological biases that need to be taken into account?
  • Which aspects of the subject are covered and which are left out?
  • Is the level of detail provided appropriate?
  • Who is the intended audience?

When examining the time factor, consider things like:

  • Is the document page or webpage dated?
  • Is the information limited to certain time periods?
  • When was it last updated?
  • Is it the type of material that needs to be updated frequently?

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