Relative Value Methodologies

Dear friends,

I am struggling to make sense of the relative value methodologies in the fixed income section.

  1. Very simply, can someone define what they mean from a practical point of view?
  2. How should portfolio managers use these relative methodologies?
  3. Are *all* the different analyses to be used together by portfolio managers for investment in bonds: Total Return Analysis, Primary market analysis, etc. Or only one of the analyses has to be used?
    Many thanks for the help.