Assign value to radio button selection

Hi, I am creating an assessment form. Each assessment task has a selection of responses:  Met Standard, Above Standard & Below Standard.

If you meet standard the score = 1, Above = 2 and Below = 0. I am using radio bottuns for selection.

How do I assign a value to the selection of the radio button so I can add up the results across multiple assessment tasks?

Thanks,

Narelle