I'm looking at some bond yields, varying coupons and maturities, same issuer (g3 govies) and non-callable. I have compared these by maturity and duration to get a sense of some rv opportunities and vs swaps. Focusing mainly on single currency curves in isolation at the moment. My aim is to really be able to find or clean the data as much as possible so as to only be seeing interesting opportunities. I.e. stripping out all obvious idiosyncrasies in the data in a systematic way. For the maturity comparisons I think I need to adjust the yields for the bonds for coupon effects. The remainder of the yield spread to par should be a reasonable indicator of 'rv', correct ? (I am deliberately ignoring funding/convexity and other sources of richeness/cheapness here to dumb things down). In the absence of being able to estimate a fair value curve yield yield spreads seem useful but for steep/flat curves they're polluted by implicit curve positions and as not durn matched sometimes make different coupons seem rich/cheap. How can I see a clearer picture of yields for similar duration bonds ? I have tried many swap related spreads, but each has their own shortcoming. For eg, par par asw, typically make the high coupons look rich, also theyre not flat outright risk. Z spreads are useful and stable but are not tradable directly (assume no liquid enough strips). Lastly, looking at yields by duration (modified) is a lot better than maturity, but, there is still a reasonable difference in yields for similar duration securities which are not mispriced, i.e. are fair value. Are there better axis to look at to compare yields ? If not, what kind of adjustments are made to factor the noise out. An example for any (preferrably all) would be very helpful (also happy to post some toy examples to illustrate my points). Pointers or resources which address these issues in detail also very welcome. Thank you.