The economics related to womens' legs

I for one have not observed hemlines of skirts for so long to make any useful inferences. But there have been many who have taken cues from watching womens' legs. According to the skirt length theory, when skirts get shorter, it's time to buy; when skirts get longer, it's time to sell. The logic behind this indicator dictates that positive markets lead to a happy nation and an atmosphere of fun. Fun times send hemlines rising, making micro minis great for the markets, while conservative floor-length dresses are bad news. Fact or Fiction? When times are good, fashions do indeed tend to show skin. The bad news is that fashions don't change until times are good, making this a lagging indicator. If you are buying and selling based on skirt length, you might be better off selling when skirts are high and buying when they are low. I have a question though, why are shorter skirts costlier than longer skirts, considering that the material costs of longer skirts are more than that of the shorter skirts(sometimes the material used is twice or even thrice the micro mini skirts). Assuming the material of the skirt is ignored, it just doesn't make sense. Maybe it is all based on perceptions and confidence and outlook of the people - all psychological factors.