# Measuring the surprise element of policy actions

Dear fellow community members,

Here is the excerpt from Bernanke and Kuttner (2005) that I need to apply to gather my data.

"A measure of the surprise element of any specific change in the Federal funds target can be derived from the change in the futures contract's price relative to the day prior to the policy action. For an event taking place on day d of month m, the unexpected, or "surprise", target funds rate change can be calculated from the change in the rate implied by the current-month futures contract. But because the contract's settlement price is based on the monthly average Federal funds rate, the change in the implied futures rate must be scaled up by a factor related to the number of days in the month affected by the change,

$$\Delta i^u = \frac{D}{D-d} (f_{m,d}^0 - f_{m,d-1}^0)$$

where $\Delta i^u$ is the unexpected target rate change, $f_{m,d}^0$ is the current-month futures rate, and $D$ is the number of days in the month. The expected component of the rate change is defined as the actual change minus the surprise, or

$$\Delta i^e = \Delta i - \Delta i^u$$

."

I need help applying the above formulas to the Australian Futures Index below. Say there is a surprise change by the RBA (Reserve Bank of Australia) on September 16, what would be the $\Delta i^u$ and $\Delta i^e$? Am i using the right data to measure this? Any help would be very much appreciated as I am very new to finance.