Once the true yields of the tradable treasury bills have been determined as described in question 2, treasury bills that coincide with or are nearest to the NITTY tenor benchmarks are used to calculate NITTY. A simple interpolation/extrapolation process is then used to match the closest Treasury bill days to maturity to their respective benchmarks. Using the simple equation of a straight line and plotting the yields against days to maturity we can arrive at the fixing.
For example; for the 1 Month fixing, the treasury bills with days to maturity just below and above thirty (30) days and their corresponding yields are used to calculate the equation of the line. If days to maturity on a tradeable treasury bill match any of the fixing benchmarks, the yields for that Treasury Bill will be selected as the fixing. Rates are quoted to meet international standards i.e. four (4) decimal places.