# Chapter 13. Peeking Data

We all know the rules of Blackjack and the information with which we have to work. But that doesn't mean that we can't look for a bit more information. This chapter looks at the gains from additional data.

"I knew all the rules but the rules did not know me." — Eddie Vedder, 2007

### What is the gain from peeking at player downcards?

Single-deck and double-deck games (pitch games) are nearly always dealt face down. This means that we do not see all of the dealt cards before making decisions unless players bust or turn over a Blackjack. Suppose that we sit at third base (far left seat) in a three-player, single-deck game. Suppose that we take a peek at the cards of the player to our right when we need to make an insurance decision. We have gained additional information about the remaining cards — the purpose behind counting cards. This chart displays the gain from peeking at one other player's cards for the purposes of insurance at penetrations from 26 to 13 cards cut off. The gain is not large, but could be increased by seeing additional players' cards.

### What about double-decks?

The gain at double-deck is clearly not worth the effort.

### Sim details

• Single-deck, H17, DAS, 3 players, Hi-Lo, truncate, Full indexes, quarter-deck resolution, penetrations from 13-26 cards cutoff by the card
• Double-deck, H17, DAS, 3 players, Hi-Lo, truncate, Full indexes, quarter-deck resolution, penetrations from 26-52 cards cutoff by the card
• Peek at one hand and no hands
• Two billion rounds each, all sims use optimal betting, full Kelly