There are several things you can do.
First of all, you can create your field as an integer or byte field, storing
1 or 0. On your data entry forms, you could represent this with a combo box
that displays Yes and No, but actually stores 1s and 0s. You could also
display it with an option group with two radio buttons, again displaying Yes
and No, but storing 1s and 0s.
Another option is to create the field as a boolean (Yes/No) field, which
will store the Yes's as -1. Then, anytime you do any math (like summing)
you can use the ABS() function to return the Absolute Value (which will be
positive).
As for the weighting, I would store the weight in a separate field, which
you can multiply with your "yes" values, to produce your weighted values.
--
--Roger Carlson
MS Access MVP
www.rogersaccesslibrary.com
http://rogersaccessblog.blogspot.com/