 How many sender strategies are there? Because we allow for the possibility of the same signal to be sent for multiple states of the world, there are two choices for which signal to send given state \(S_1\) and two choices for which signal to send given state \(S_2\). This means there are four possible sender strategies. These strategies are as follows (where \(\mathrm{`}X \rightarrow Y\text{'}\) means that when the state of the world is \(X\) the sender will send signal \(Y)\):