Put parentheses around the power and format the field with the appropriate size and number of decimal places: 2^(-2) = 0.25
BTW, you can also use fractional powers for roots: 4^0.5 = 2
I tested with parentheses and without and got the correct answer .25
I would guess there is another problem amiss with your calculation.
You are right. Unexpected since the equation is for a vital medical condition that you'd have thought people would get right (!), but it was incorrect.
The ^ works whether using a positive/ negative power.