---
title: Kendall's Tau - Definition & Examples | RGM® Glossary
url: https://realgrowthmatters.com/glossary/kendalls-tau/
updated: 2026-06-10
source_html: https://realgrowthmatters.com/glossary/kendalls-tau/
---

Growth Glossary — Definition

SHT KENDALLS-TAU

# Kendall's Tau

Non-parametric rank correlation. A working definition from the RGM marketing glossary.

Non-parametric rank correlation.

Term
:   Kendall's Tau

Field
:   Statistics & Analytics

Category
:   Statistics & Analytics

## Definition in plain terms

Look at it this way.Kendall's Tau is an analytical concept your team should define once. A loose definition misaligns budgets and reporting.

Non-parametric rank correlation.

Kendall's Tau sits in Statistics & Analytics; it is an analytical concept. Define it once and the reporting holds together.

## How it operates

Start here.Kendall's Tau is no fixed dial. How it behaves depends on your audience, your channel mix, and the strategy around it.

Kendall's Tau behaves unlike a fixed rule. An early-stage brand and a mature one will apply Kendall's Tau on different terms. The mechanics follow the inputs around it. Treat Kendall's Tau as a buzzword and the reporting misleads; agree on it and the numbers hold.

One rule always holds. Settle the scope of Kendall's Tau up front, then build the plan. Get it backwards and Kendall's Tau becomes a word everyone uses and no one shares. Worth a slow read.

## When teams use it

Keep this in mind.Use Kendall's Tau when it changes a choice. If it is not driving a decision, it is vocabulary, not leverage.

Bring Kendall's Tau in when a live choice hangs on it. In statistics & analytics work, that usually means one of three moments. Away from a decision, Kendall's Tau is background, not a lever.

1. **Setting budget.** Kendall's Tau signals which line earns the marginal spend.
2. **Choosing a metric.** Kendall's Tau reveals if the metric measures real impact.
3. **Comparing options.** Kendall's Tau adjusts a compare so the gap is honest.

## A worked example

Pick one definition.The walk-through runs Kendall's Tau through work modeled on Netflix, so the concept meets real constraints.

Take Netflix. During a sequential-testing rollout, the team made Kendall's Tau the deciding input, not an afterthought. They set a baseline first, agreed one definition of Kendall's Tau, and only then read the result: average test length fell 28%. The number matters less than the order.

Worked example for Kendall's Tau -- illustrative figures, RGM analysis

| Stage | Action | Why it mattered |
| Baseline | Read the starting point before any change to Kendall's Tau. | Something concrete to compare to. |
| Define | Locked the scope of Kendall's Tau so it stayed stable. | A shared definition up front. |
| Act | A sequential-testing rollout — one variable. | Cause and effect, isolated. |
| Result | Average test length fell 28% | A decision the data earned. |

Treat the Kendall's Tau figures as illustrative, labeled RGM analysis. Reuse the sequence, not the digits.

## Common mistakes

Here is the short version.Teams slip on Kendall's Tau in four familiar ways. Each makes a soft assumption look like a precise number.

- **One blanket rule.** Applying Kendall's Tau the same way everywhere. Split it by audience, channel, and business model.
- **No context.** Reporting Kendall's Tau with no baseline. A bare number cannot be judged.
- **Chasing the word.** Optimizing Kendall's Tau for its own sake. Check it tracks a real outcome.
- **Apples to oranges.** Comparing Kendall's Tau across firms raw. Adjust for pricing and cycle before you read it.

## Questions teams ask

What does Kendall's Tau mean?

Non-parametric rank correlation. Agree the scope of Kendall's Tau before the planning starts.

Why does Kendall's Tau matter for marketers?

Kendall's Tau matters because vague vocabulary breaks strategy. A precise, shared definition keeps a team aligned.

Where does Kendall's Tau get used?

Kendall's Tau informs a decision -- most often a budget, a metric choice, or a comparison. The Netflix example above shows the pattern.

What is the most common mistake with Kendall's Tau?

Using Kendall's Tau flat across every segment and showing it without context. Both make a guess look exact.

What does Kendall's Tau mean?
:   Non-parametric rank correlation. Agree the scope of Kendall's Tau before the planning starts.

Why does Kendall's Tau matter for marketers?
:   Kendall's Tau matters because vague vocabulary breaks strategy. A precise, shared definition keeps a team aligned.

Where does Kendall's Tau get used?
:   Kendall's Tau informs a decision -- most often a budget, a metric choice, or a comparison. The Netflix example above shows the pattern.

### Read next

### Related terms