If your goal is to optimize the dihedral angle to obtain no yaw/roll coupling, a low wing layout normally requires about one degree or so of dihedral, and a shoulder wing layout a roughly equal amount of anhedral. This is because of the influence that the fuselage exerts on the wing when the airplane is yawed. For example, in a yaw to the right, the air pressure is higher on the left side of the fuselage, which tends to produce a downforce on the left wing, and an equal upforce on the right wing, causing a low wing airplane to tend to roll left. The result is adverse roll, which can be nullified by the correct dihedral, which depends on the depth of the fuselage and the wing shape. In a high wing layout, the rolling tendency is in the opposite direction, a proverse roll, in the same direction as the yaw, requiring anhedral to remove.

Getting the dihedral/anhedral exactly right is difficult. Dihedral is difficult to change after the airplane is built, unless it has strut-braced wings. Some competition aerobatic pilots, after flight testing, slightly bend the joiner tube between the panels of a two-piece wing, until all yaw/roll coupling is removed.