Hello,

Tier-III paper is given by specific candidates who are interested only for the post of “Statistical Investigator Grade II” & “Compiler”. It is a descriptive test  to see the writing skills of the candidates in their chosen language. Offline exam carries 100 marks, to be solved in 60 minutes. You can refer to the books by Arihant Publication or Wiley's. The essay books are specially for this preparation.

Hope this helps. All the best!