If one's analysis is purely technical (price & volume only), and price movements are random, as Burton Malkiel states in his best seller 'A Random Walk down Wall Street', then it is mathematically impossible to profit, and any gains are the result of lucky guesswork. My own trading experience tends to confirm this view.

If the market is "trending", then there is a bias to price movement, i.e. it is not random. Under such circumstances, one can potentially profit by trading in the direction of the trend, cutting losses short, and letting profits run as long as possible (creating the situation described above, where the average win > average loss).