---
title: Relevance Index metric
slug: '3318'
canonical_url: https://docs.coveo.com/en/3318/
collection: coveo-analytics
source_format: adoc
---
# Relevance Index metric
The exact formula is part of Coveo's secret sauce to determine the relevance of [queries](https://docs.coveo.com/en/231/) and [items](https://docs.coveo.com/en/210/).
This index combines many indicators measuring relevance such as the clickthrough ratio (low is bad), the [Average Click Rank](https://docs.coveo.com/en/2836/) (high is bad), and how frequently the item is queried or the query submitted (high frequency has more impact on relevance).

Lower [Relevance Index](https://docs.coveo.com/en/2838/) values mean users aren't finding what they're looking for.
Sorting queries or items by ascending **Relevance Index** is our recommended approach to focus on high-impact queries or items with [relevance issues](https://docs.coveo.com/en/2017/).

> **Note**
>
> The **Relevance Index** and **Relevance Index (Legacy)** values are colored to show if they're good, bad, or neutral.
> 
> The predefined thresholds for each [metric](https://docs.coveo.com/en/263/) are the following:
> 
> * **Relevance Index**: < 0.3 = bad (red), >= 0.3 and \<= 0.7 = neutral (black), and > 0.7 = good (green)
> * **Relevance Index (Legacy)**: < 0.5 = bad (red), from 0.5 to 0.7 = neutral (black), and > 0.7 = good (green)

## Main differences between Relevance Index and Relevance Index (Legacy)

### Concept of confidence

The new **Relevance Index** introduces the concept of confidence.
For the same proportion of **Search Event Clickthrough** and the same **Average Click Rank**, the new **Relevance Index** value will increase proportionally to the number of times a user query is performed.
In the same scenario, the **Relevance Index (Legacy)** value would have decreased.

The confidence goes both ways: good queries get a score higher than `0.5` that increases with the frequency of the query, and bad queries receive a score lower than `0.5` that decreases with the frequency of the query.
The higher the frequency, the farther the **Relevance Index** is from the `0.5` mark.

**Example**

For the same **Search Event Clickthrough** (that is, 40 %) and an **Average Click Rank** of 3, the table below shows how a positive change in the **Search Event Count** metric impacts the **Relevance Index** and **Relevance Index (Legacy)** values.

[cols="5*^", options="header"]
|===
| Search Event Count
| Clickthrough (%)
| Average Click Rank
| Relevance Index
| Relevance Index (Legacy)

| 5
| 40
| 3
| 0.63
| 0.70

| 10
| 40
| 3
| 0.68
| 0.65

| 50
| 40
| 3
| 0.80
| 0.56

| 100
| 40
| 3
| 0.84
| 0.52

| 500
| 40
| 3
| 0.87
| 0.46
|===

### Average Click Rank value impact

An **Average Click Rank** value change has less impact for the same number of queries and clickthrough ratio in the new **Relevance Index** formula.
The value changes gradually.

**Example**

For the same **Search Event Count** (that is, 500) and a clickthrough of 40%, the table below shows how a change in the **Average Click Rank** metric impacts the **Relevance Index** and **Relevance Index (Legacy)** values.

[cols="5*^", options="header"]
|===
| Search Event Count
| Clickthrough (%)
| Average Click Rank
| Relevance Index
| Relevance Index (Legacy)

| 500
| 40
| 1
| 0.87
| 0.82

| 500
| 40
| 4
| 0.85
| 0.42

| 500
| 40
| 8
| 0.78
| 0.35

| 500
| 40
| 12
| 0.64
| 0.32

| 500
| 40
| 16
| 0.56
| 0.30
|===

### Score of queries with a Clickthrough of 0%

The new **Relevance Index** attributes a low score to queries with a clickthrough of 0 %.

**Example**

For the same **Search Event Count** (that is, 500) and an **Average Click Rank** of 3, the table below shows how a change in the **Search Event Clickthrough** metric impacts the **Relevance Index** and **Relevance Index (Legacy)** values.

[cols="5*^", options="header"]
|===
| Search Event Count
| Clickthrough (%)
| Average Click Rank
| Relevance Index
| Relevance Index (Legacy)

| 500
| 0
| 0
| 0
| 0.72

| 500
| 1
| 3
| 0.08
| 0.53

| 500
| 10
| 3
| 0.41
| 0.43

| 500
| 25
| 3
| 0.7
| 0.44

| 500
| 50
| 3
| 0.91
| 0.48
|===