Think back to one of your high school science projects--a hypothesis was created, variables were included and tested and a thorough analysis of the project was done. Fashion is the same way.
In order to consider yourself fashionable, one must first form a hypothesis of the style they desire to portray. When doing this, the fashionista will consider the different outcomes of the style they desire such as environment, body shape and personality.
Once this is decided, the hypothesis is then tested with variables. The constant variable is very similar to the dependent variable: The difference is, the constant variable is to achieve your fashion persona even with the changes caused by the independent variable such as accessories and outerwear.
Once the variables are tested, the analysis of the fashion created takes place. The fashionista analyses the finished product for factors such as uniqueness, timelessness and signature.
Uniqueness sets the fashionista apart from the pack. Even though he/she follows all of the trends, they are able to take them and make them their own.
Timelessness shows the fashion sense of the fashionista, who is able to find pieces that will survive long after the trends come and go, but still manage to make every outfit fresh and modern.
Finally signature gives the fashionista individuality. Because trends drive fashion, it is important that the fashionista is able to establish a style that is recognizable, and more importantly, envied.
There you have it, the scientific method of fashion.