spy611.com serves stock market predictions to you.
This site uses backtests to study the accuracy and effectiveness of simple machine learning models on S & P 500 data.
If a backtest suggests that a model issues effective predictions on past data, obviously that does not mean the model can predict the future.
If, however, a model issues ineffective predictions on past data, I would not want to use that model to predict future S & P 500 behavior.
If you have questions, contact Dan: firstname.lastname@example.org