# Sticky image turns into add-to-cart bar on scroll: +3.7% conversion

- Outcome: Flat / inconclusive
- Page type: Product page (Ecommerce)
- Elements: Sticky add-to-cart bars
- Test run by: [Clean Commit](https://liftarchive.com/practitioners/clean-commit/)
- Commentary by: LiftArchive (our analysis, not theirs)
- Original source: https://cleancommit.io/ab-tests/transforming-the-sticky-add-to-cart-into-a-persistent-bottom-bar/
- Page: https://liftarchive.com/test/cleancommit-transforming-the-sticky-add-to-cart-into-a-persistent-bott/

Turning a sticky product image into a sticky add-to-cart bar, once shoppers scrolled past the main button, showed a 3.7% lift in conversion rate. Clean Commit ran this test for an anonymized Shopify store. With only a 71.6% probability of beating the original, we count it as inconclusive.

## Result

**+3.7% conversion**

- Conversion rate rose 3.7%, with a 71.6% probability of beating the original. That is far from significant.
- Revenue per visitor rose 23.1%, driven by an 18.1% rise in average order value.
- Click-through rate rose 17.0%, and bounce rate fell 21.9%.
- On mobile, conversion rate rose 9.3%. On desktop it fell 14.2%, a negative result for that device.

## Control

Product pages had a sticky product image but no sticky buy bar. Once the main add-to-cart button scrolled away, there was no button in view.

## Variant

After the main button left the screen, the sticky image changed into a bar fixed to the bottom. The bar showed the product title, price and an add-to-cart button.

## Why it likely came out this way (our reading)

- Keeping a buy button in view gives shoppers a clear path to purchase at any point on the page.
- On small screens the main button disappears quickly, so a bar helps more on mobile.
- On desktop, a fixed bar may feel like clutter, which could explain the drop there.
- The big jump in order value is hard to tie to a sticky bar and may be noise.

## Caveats

Not statistically significant, and no sample size or duration was shared. Desktop conversion fell 14.2% while mobile rose.

## How to run this test

- Hypothesis: If we show a sticky add-to-cart bar once the main button scrolls out of view, then conversion rate will rise because shoppers always have a clear way to buy.
- Primary metric: Conversion rate, split by device
- Guardrail: Desktop conversion rate
- Guardrail: Average order value
- Guardrail: Bounce rate
- Who should test it: Stores with long product pages and mostly mobile traffic. Consider limiting it to mobile, since desktop went the wrong way here.

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Credit: Clean Commit ran this test and owns the result. Summary and commentary by LiftArchive (https://liftarchive.com/test/cleancommit-transforming-the-sticky-add-to-cart-into-a-persistent-bott/).
Usage: Free to use, quote and build on, with credit and a link: name the practitioner or organization that ran the test and link to its LiftArchive page. The results belong to the practitioners who ran and shared them; the summaries and commentary are LiftArchive's.