Howto
This module is designed to calculate sperling's ride index. This is written in Visual basic to be attached as module in  an Excel (MSOffice 2000) spreadsheet.
To run the module , following steps are required
  1. Copy the file "calculate_RI.txt" and rename as "calculate_RI.bas" to  a suitable location.
  2. Open the data in Excel
  3. From the menu, choose "Tools" -> "Macro" -> "Visual Basic Editor"
  4. In the Visual Basic editor window menu, choose "File" ->"Import" , choose   " calculate_RI.bas".
  5. Close the visual basic editor window
  6. From the menu, choose "Tools" -> "Macro" -> "Macro" ->"run", choose " calculate_RI.bas".