From Knitting Magazine Supplement:

This super-simple bobble hat looks really funky and is a perfect project for beginners.

Size:
Circumference 54 cm
Depth 25 cm without pompom

Needle:
The patterns requires 20 mm (US size 36) needles.

Yarn:
1 x 150g ball in 605 Love Bug, 620 White Cotton or 600 Shadow