I need help in understanding the different figures for Vanugard Short Term Investment Grade Bond Fund.   The TYD Return is 1.20% and the Yield is 4.50%.   What does that wide difference mean?    The price of the bond fund has fallen only from $10.65 to $10.51 Jan. 2, 2008 to Jan. 27, 2008.    I simply do not understand Yield and YTD Return.  

Thank you,

Larry