Knit hats are great for keeping your head and ears warm when it's chilly out. But they're not so great when you want (or need) to wear your hair in a ponytail. That's when the Calorimetry is perfect.
I knit mine up in some lovely handspun gifted to me by ilikecake. Isn't the yarn gorgeous? I made a few modifications to the pattern since I had read on Ravelry that the pattern comes out a bit on the larger side.
I cast on 96 stitches instead of 120 and repeated row 5 for a total of 10 times instead of 15. Even with the mods, I think it still comes out big because of the stretchiness of the rib. I'd cast on less stitches the next time.