Are you having a good hair day or a bad hair day? This may seem like a trivial question – but for women, it’s something that can affect their happiness and even their professional success. That’s according to a study done by Yale University and Procter-and-Gamble’s Pantene hair-care brand. After surveying more than 4-thousand women across eleven countries, the study found HAIR is one of the most important ways women express themselves to the world.