The outer section of the Robin wing has dihedral, which gives increased stability in bank and in turns.
The outer wing section also has a high degree of washout, so it provides minimal lift and drag in cruise, but gives extra lift at high angles of attack, improving low speed stability, maintaining aileron effectiveness near the stall, and reducing the stall speed. The inner section produces most of the lift in cruise, giving high wing loading for a smoother ride. The result is a very safe handling and responsive aeroplane that is a pleasure to fly!
Virtually all wings, other than in some military combat types, incorporate positive dihedral for stability but to twist a wing that has constant dihedral to provide washout near the outer ends is complicated and, therefore, expensive, which is why you see stall strips on the inner section of some wings. Stall strips are really a fudge to cause the inner part of the wing to stall before the outer part. The craftsmen-made wooden structure of the Robin (originally Jodel) wing effectively combines constructional and aerodynamic efficiency without the compromises of other designs.