# WOW_REL
URL: https://docs.valsight.ai/wow-rel/
Description: Returns the relative growth for each week compared to the previous week (week-over-week).
**Category:** [Compare periods](/compare-periods/)

## Overview

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

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

## Syntax

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

## Parameters

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

**MissingValueBehaviour options:**

* `"IGNORE_MISSING"`: Missing rows are skipped. This is the default.
* `"MISSING_AS_ZERO"`: Missing rows are treated as 0.

## Examples

### Default: ignoring missing values

This example shows WOW\_REL with the default behavior. The missing weeks are skipped and no result is produced for them.

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

| Week     | Value |
| -------- | ----- |
| 2025-W01 | 200   |
| 2025-W02 | 300   |
| 2025-W03 | 450   |
| 2025-W04 | 500   |
| 2025-W06 | 100   |

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

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

| Week     | Calculation       | Result |
| -------- | ----------------- | ------ |
| 2025-W02 | (300 - 200) / 200 | 0.5    |
| 2025-W03 | 150 / 300         | 0.5    |
| 2025-W04 | 50 / 450          | 0.11   |

### Treating missing values as zero

With MISSING\_AS\_ZERO, gaps are filled with 0, producing results for every week including those without input data.

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

| Week     | Calculation       | Result |
| -------- | ----------------- | ------ |
| 2025-W02 | (300 - 200) / 200 | 0.5    |
| 2025-W03 | 150 / 300         | 0.5    |
| 2025-W04 | 50 / 450          | 0.11   |
| 2025-W05 | (0 - 500) / 500   | -1     |
| 2025-W07 | (0 - 100) / 100   | -1     |

2025-W06 is not present in the result: even with MISSING\_AS\_ZERO, dividing by a zero previous value causes a division by zero, so the entry is dropped.

## Related

| Function                  | When to use instead                                                           |
| ------------------------- | ----------------------------------------------------------------------------- |
| [WOW\_ABS](/wow-abs/)     | When you need the absolute difference week-over-week instead of a percentage. |
| [YOY\_REL](/yoy-rel/)     | When you need the percentage change on a yearly basis instead of weekly.      |
| [DELTA\_REL](/delta-rel/) | When you need relative change along any dimension, not just time.             |