> ## Documentation Index
> Fetch the complete documentation index at: https://docs.creditbenchmark.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Opinion Change Indicator

> The Opinion Change Indicator distinguishes genuine bank opinion changes from consensus rating moves caused by shifts in the contributing bank population.

## Why It Exists

The [Consensus PD](/methodology/consensus-pd) is a simple average — which means it is sensitive to both **what banks think** and **who is contributing**. When the contributor pool changes, the average can shift even if no bank has changed its view.

This means the Consensus PD can move for two very different reasons:

* **Opinion change** — one or more banks changed their PD estimate for this entity
* **Depth change** — the contributing bank population changed; a bank joined, left, or both

Telling them apart is critical to interpreting the data correctly.

## How It Works

The **Opinion Change Indicator (OCI)** measures the net rating change across banks that contributed in both the current and prior period — **holding the population constant** to isolate genuine shifts in credit sentiment.

### Formula

The OCI tracks credit sentiment at the **individual contributing bank level** — for each same-bank contributor, we calculate whether their view moved toward improvement, deterioration, or held steady month-on-month.

Each is assigned a directional signal (**+1**, **−1**, or **0**), and those signals are summed to produce a net read on market direction:

$$
\text{OCI}_t = \sum_{b \,\in\, B_t \,\cap\, B_{t-1}} \text{sign}\bigl( f(PD_{b,t-1}) - f(PD_{b,t}) \bigr)
$$

Where:

* $B_t$ = set of contributing banks at time $t$
* $f(PD)$ = rating scale mapping function returning a notch index
* A positive result indicates net improvement; negative indicates net deterioration

By restricting the sum to $B_t \cap B_{t-1}$ — banks present in both periods — the OCI strips out any movement caused by banks joining or leaving the contributor pool.

<Tip title="The key rule">
  If the CCR or Consensus PD moved but the OCI is **Stable**, the move reflects a change in who is contributing — not a change in credit opinion. Weight it accordingly.
</Tip>

## OCI Values

The OCI is published as a directional indicator. On the [single entity page](/delivery-channels/webapp-pages/entity), each contributing bank gets an arrow:

* **Improving** — net same-bank view moved toward lower PDs (green arrow)
* **Stable** — no net change among same-bank contributors (no arrow)
* **Deteriorating** — net same-bank view moved toward higher PDs (red arrow)

## Use in PD Aggregates

The OCI feeds into the [PD Aggregates methodology](/methodology/pd-aggregates/methodology), where population-controlled time series are constructed to track genuine credit sentiment over time — stripping out noise from contributor turnover.