Hi Bill,
Dihedral>
Basically this is a stability factor, tends to right the craft laterally.
All airplnes without ailerons should have some dihedral.
Amount depends up other design factors, such as wing location
vertically. A high wing design requires less than a low wing for
example. Also amount of lateral area which is depicted by a side
profile. Lots of L.A. requires less dihedral.
A high wing cabin style craft does well with 5 degrees,
A low wing would need 10 deg, or more.
Excessive dihedral limits maneuverability.
Hope this is of some help.
Good luck!

Hal deBolt