Q. How do I find dividend yields for indices and individual stocks?

For companies, see Mergent Online.

For indices see Datastream (3rd floor (Room M3-53B) Humanities/McLennan library).

Open Excel
Choose Datastream-AFO
Choose Time Series Request
To get the dividend yield for the S&P 500 enter 
the Datastream mnemonic: S&PCOMP
Enter the datatype DY for dividend yield
Enter the frequency
Enter the time period you want. 

For the dividend yield for individual stocks, use the Datastream mnemonic
for that stock.
For example U:IBM

See our quick video on how to use Datastream.