Based on Entry Another Cell is Populated with a Value

Based on an entry in a cell (either La Nina, Neutral, or El Nino), I want a numeric value to be populated in another cell in my spreadsheet. This will allow me to do further calculations. In this basic example, my entry cell is Cell I3 where either La Nina, Neutral, or El Nino will be entered. If cell J2 is La Nina, cell I3 will be populated with -0.5 (now this will change with some other cells in my spreadsheet). If cell J2 is Neutral, cell I3 will be populated with 0. If cell J2 is El Nino, cell I3 will be populated with 0.5. I tried doing a series of If Then statements, but get #VALUE! Here is my equation...

=IF(I3=E3,-0.5),IF(I3=E4,0),IF(I3=E5,0.5)

If there is a better way of doing multiple selections, please let me know.

Thanks in Advance!

Jeff B