Hivi kuna hili swala la measuring of the stock market but i get cofusion. Please, i would like to know how they know the stock of certain company increase/decrease? Also i would like to know if Africa (Tanzania if possible) have any such company dealing with such stock market index. Example of indexes i know are American s*p 500 , the Japanese Nikkei 225 and the British ftse 100. Thank you for your assistance.