Raising simply to gain information is a tricky play and shouldn't be done often. Generally you should consider any information gained as an extra benefit of a raise you are making for other reasons.

Let's say with a pair of kings on fourth street in seven-card stud you raise an open pair of 9s. Your opponent reraises. You decide that opponent has three 9s and fold. By risking one bet (your raise), you save as many as three bets you might otherwise have called on fifth street, sixth street, and on the end. Your savings is even greater when the bet doubles after fourth street. A trial-balloon raise on a $10 round could save you three $20 calls later.

Nevertheless, raising just to gain information is tricky. For example, if that open pair of 9s just calls your raise, can you be sure that opponent doesn't have three 9s? What to do on the next round may still not be clear to you. That is why you should generally reserve your raises for other purposes and consider whatever information you gain from your opponents' responses as an added benefit.

• Raising to Get More Money in the Pot
• Getting More Money in the Pot by Not Raising
• Raising to Drive Out Opponents
• Raising as a Means of Cutting Down Opponents' Odds
• Raising to Get a Free Card
• Raising to Gain Information
• Raising to Drive Out Hands
• Raising Versus Folding or Calling
• Check-Raising