Want to ask for CDS price in the book stated it is 1+ (Fixed coupon - CS spread)* delta eff spread duration.
So when calculating the price of CDS, I assume it is like 104.25 and 108.5 in the example , and use these two figures to derive the return.
However, the textbook answers derives 95.75 and 91.5 and calculate the return in the similar fashion.
My question is
i) which method is correct
ii) does this method changes if I enter the position as protection buyer and protection seller
iii) return calculation is always ( new price - old price )/old price ( I can judge the sign myself, but at least if this formula is correct)
