# YOY_REL
URL: https://docs.valsight.ai/yoy-rel/
Description: The YOY_REL function returns the relative growth for each year compared to the previous year (year-over-year).
**Category:** [Compare periods](/compare-periods/)

## Overview

The **YOY\_REL** function **returns the relative growth for each year compared to the previous year** (year-over-year).

Use this function when you need the percentage change between consecutive years.

## Syntax

`YOY_REL('Node' [, "MissingValueBehaviour"])`

**Example usage:** `YOY_REL('Revenue')`

## Parameters

| Parameter                 | Description                                                                  | Type           | Required | Default            |
| ------------------------- | ---------------------------------------------------------------------------- | -------------- | -------- | ------------------ |
| **Node**                  | Input node, specified using the node name in single quotes (e.g.`'Revenue'`) | Node reference | Yes      | --                 |
| **MissingValueBehaviour** | How missing values in the time series are treated                            | Keyword        | No       | `"IGNORE_MISSING"` |

**MissingValueBehaviour options:**

* `"IGNORE_MISSING"`: Missing rows are skipped. A result row is only produced where both the current year and the previous year have values. This is the default.
* `"MISSING_AS_ZERO"`: Missing rows are treated as 0.

## Output shape

| Aspect         | Behavior                                                                                                                                    |
| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| Dimensionality | Same as input.                                                                                                                              |
| Time range     | The first year is always dropped (no previous year to compare against). Additional years may be dropped depending on MissingValueBehaviour. |
| Values         | Each value is `(current_year / previous_year) - 1`. The result is a ratio, not a percentage.                                                |
| Row count      | Reduced. At minimum, the first year is removed. With IGNORE\_MISSING, years adjacent to gaps are also removed.                              |

## Watch out

* The input must have a **Year** level. If the input does not contain a Year level, the function fails.
* The result is a **ratio**, not a percentage: 0.5 means +50%, -1 means -100%.
* **Division by zero** occurs when the previous year's value is 0. The affected cell is silently dropped (N/A). This is especially relevant with MISSING\_AS\_ZERO, where gaps are filled with 0.
* With **MISSING\_AS\_ZERO**, the function produces results at years where only the previous year has data, treating the missing current year as 0. This leads to a result of -1 (a 100% decline). Be cautious when interpreting these results.

## Examples

### Default: ignoring missing values

This example shows YOY\_REL with the default behavior.

**Input node:** `'Profit'`

| Year | Value |
| ---- | ----- |
| 2025 | 200   |
| 2026 | 300   |
| 2027 | 450   |
| 2028 | 500   |
| 2030 | 100   |

**Formula:** `YOY_REL('Profit')`

**Equivalent to:** `YOY_REL('Profit', "IGNORE_MISSING")`

| Year | Calculation       | Result |
| ---- | ----------------- | ------ |
| 2026 | (300 - 200) / 200 | 0.5    |
| 2027 | (450 - 300) / 300 | 0.5    |
| 2028 | (500 - 450) / 450 | 0.11   |

The first year (2025) has no previous year to compare against. The missing year 2029 causes 2030 to also be excluded because no valid previous year exists.

### Treating missing values as zero

With MISSING\_AS\_ZERO, gaps are filled with 0. This produces results for every year but can cause division by zero when the previous year has no data.

**Formula:** `YOY_REL('Profit', "MISSING_AS_ZERO")`

| Year | Calculation       | Result |
| ---- | ----------------- | ------ |
| 2026 | (300 - 200) / 200 | 0.5    |
| 2027 | 150 / 300         | 0.5    |
| 2028 | 50 / 450          | 0.11   |
| 2029 | (0 - 500) / 500   | -1     |

The missing year 2029 is treated as having value 0, which produces a -1 result (100% decline). Year 2030 attempts to divide by 0 (the previous year 2029 was treated as 0), so the entry is dropped from the result.

## Related Functions

| Function                  | When to use instead                                                                        |
| ------------------------- | ------------------------------------------------------------------------------------------ |
| [YOY\_ABS](/yoy-abs/)     | When you need the absolute difference to the previous year instead of a percentage.        |
| [DELTA\_REL](/delta-rel/) | When you need relative change along any dimension, not just time.                          |
| [CAGR](/cagr/)            | When you need compound growth over multiple periods instead of a single-period comparison. |