Has anyone used Weka? I just started to read more about Weka and it seems like a very popular data mining tool with machine learning algorithms built in. Maybe I just can't connect the dots here. I am not sure how it applies in the world of trading when prediction is the key. One of the example I found online is related to fundamental analysis with Weka. You input Profit/loss, debt, revenue, etc as attributes and some initial classes (buy, sell, hold). But I am completely not sure how it produces the results that says the stock should be a buy/sell/hold. How does it know the it is correct to buy(hold/sell) without having attributes of future prices? I understand the attributes are there as variables for correlations (i.e. if revenue is x, P&L is y, etc, then buy). I can't get how buy is verified without another price is inputted. To me, you know the buy is correct only after later prices confirm that the buy is correct. Maybe I am just confusing more readers here. Any explaination would be helpful. Thank you.