This is a relatively simple question but I have a global index of bonds and have been asked to calculate the DTS of each bond within the index. I have only the OAS and effective duration. I have no spread duration measure.
I have read in a few places that Effective Duration is equal to Spread Duration when there are no treasury bonds which this is the case. Can I take effective duration therefore to be spread duration? This doesn't quite make logical sense to me as one is the impact on interest rates and the other spread.