---
title: What is Novelty effect?
url: https://markin.ai/glossary/novelty-effect
category: Experimentation and causality
---

# Novelty effect

> The novelty effect is a temporary response lift caused by a change being new rather than better. It decays as customers habituate, so short tests systematically overstate the durable impact of visible interface, creative or messaging changes.

## Why it matters for ARPU

Growth programmes that ship on week-one results accumulate wins that quietly disappear, which is a common reason reported gains never show up in annual ARPU.

## Related terms

- [A/B test](https://markin.ai/glossary/ab-test), An A/B test randomly assigns customers to two or more variants and compares a pre-declared metric between them.
- [Incrementality](https://markin.ai/glossary/incrementality), Incrementality is the portion of an outcome that would not have happened without the action.
- [Cohort analysis](https://markin.ai/glossary/cohort-analysis), Cohort analysis groups customers by a shared starting characteristic, usually acquisition month, and follows each group over time.
- [Guardrail metric](https://markin.ai/glossary/guardrail-metric), A guardrail metric is a measure an experiment must not damage even if the primary metric improves: unsubscribe rate, complaint volume, margin, support contacts, app uninstalls.

## Go deeper

- [From creative volume to decision volume](https://markin.ai/blog/creative-volume-to-decision-volume), Why novelty flatters creative tests.
- [Growth optimization](https://markin.ai/solutions/growth-optimization), Durability checks after launch.

Source: https://markin.ai/glossary/novelty-effect