---
title: "Impact metric in RUM smartboard"
slug: "impact-metric-in-rum-smartboard"
updated: 2023-01-06T15:49:20Z
published: 2023-01-06T15:49:19Z
canonical: "docs.catchpoint.com/impact-metric-in-rum-smartboard"
---

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

# Impact metric in RUM smartboard

## Overview

The **Impact** metric in the RUM Smartboard takes whatever performance metric is selected and normalizes it against the number of pageviews for each segment in a given dimension, providing a [weighted average](https://en.wikipedia.org/wiki/Weighted_arithmetic_mean). The problem it solves is that if you just sort by average performance, that dimension may have a skewed average for a very small amount of traffic, so the overall effect of that segment on user experience might not be significant. By looking at **Impact**, you can more easily see which performance problems are significant. ![](https://cdn.document360.io/cb4af8f9-6751-4fd2-b39c-07aae832badb/Images/Documentation/360006926852-mceclip0.png?sv=2026-02-06&spr=https&st=2026-10-13T12%3A43%3A43Z&se=2026-10-13T13%3A43%3A43Z&sr=c&sp=r&sig=nEuzzQCa2HwgePhcnmM6aAIhlZz8wocTFy03fjPObW8%3D)

## How Impact is calculated

Assume we have seven pageviews from the New York region and four pageviews from Los Angeles.

Let’s say the pageviews have the DNS times given below:

![](https://cdn.document360.io/cb4af8f9-6751-4fd2-b39c-07aae832badb/Images/Documentation/360006924632-mceclip0.png?sv=2026-02-06&spr=https&st=2026-10-13T12%3A43%3A43Z&se=2026-10-13T13%3A43%3A43Z&sr=c&sp=r&sig=nEuzzQCa2HwgePhcnmM6aAIhlZz8wocTFy03fjPObW8%3D)

Let **T** be the total number of page views: $T = 7+4 =11$

Let **A** be the average of the DNS times accross both the regions: $A = (50+44+76+33+54+25+67+100+95+66+33)/11 = 58.45 ms$

Now, **% Impact of New York = Sum of DNS times from New York / (A * T)** $= (50+44+76+33+54+25+67) / (58.45*11)$ $= 54\%$

Similarly, **% Impact of Los Angeles** = $(100+95+66+33) / (58.45\*11)$ $= 46\%$

If we just consider the average of the DNS performance, we get **New York DNS(Avg) = 49.86ms** **Los Angeles DNS(Avg) = 73.5ms**

You can see that even though the average for LA is higher, NY has greater impact since it generated more traffic.