Why is the state-action value function used more than the state value function?

In reinforcement learning, the state-action value function seems to be used more than the state value function. Why is it so?

• What do you mean by "more"? Btw, if I understand your question correctly, it is because in a non-deterministic setting, you won't know which action to select simply from the state values. – Hai Nguyen Feb 14 '20 at 7:31
• @HaiNguyen thanks. What happens in the case of deterministic setting – Bhuwan Bhatt Feb 19 '20 at 16:37
• If you know what state you will end up after taking an action (for example if you walk in a maze you always know your next position after you take a step), you can use the value function of possible next states and pick the action that leads to the highest value. – Hai Nguyen Feb 20 '20 at 11:51

• what did you mean by simulate all possible actions one step ahead? – gfdsal Apr 28 '20 at 14:59