Oddness in the rankings

Hi, my name is Ahmad Kushay. I am a first year undergraduate student at the Bandung Insitute of Technology.
I was looking at QS World University Rankings by Subject 2015: Country Reports - Indonesia and I found some oddness in it. You see, ITB has no social sciences major except Art & Design, Entrepeneurship and Management. So how come ITB is featured as the top 5 Indonesian universities in subjects like Law, Politics, etc?
How does this ranking is done? Was there a mistake in data processing or is it because of something else? Thank you.