PokerSnowie Online Manual
The error rate measures the EV given up. You may, however, have a good error rate and a poor balance as a result of the weak/medium/strong ratio. The balance page shows you how balanced your play has been.
The 'Call' block compares your number of calls with the number of calls PokerSnowie would have played, split by each betting round. 100% is the perfect value, a number higher than 100% means that you called too often and a number lower than 100% means you didn't call enough.
The 'Bet' block does the same thing for all your bets, but split by bets with weak (as a bluff), medium and strong (for value) hands. Again 100% is best, but additionally it is important to have as similar a score as possible for each weak / medium / strong bracket. 100% weak, 100% medium and 100% strong is best, but for example 150% weak and 150% strong is a lot better than 150% weak and 50% strong. 150%/150% indicates a too high frequency of betting, but at least the ratio between weak and strong hands is right. 150%/50% is very bad, the balance is quite wrong and the opponent could easily exploit this.
The 'Raise' block has the same structure as the 'Bet' block.
Note that you can click on the numbers below the percentages, which is the number of times the player actually played that type of move. This automatically sets the filter so that you can browse through these specific actions.