A/B subject testing vs multivariate testing

A/B subject testing vs multivariate testing

Most sequencers test subject lines. Whether to go beyond two variants is the question.

Simple A/B (most senders) Pros:
— Reaches significance fast on smaller lists
— Clear winner, easy to act on
— Built into Instantly, Smartlead, Lemlist

A/B Cons:
— Tests one variable at a time
— Slow to optimize the full email

Multivariate (subject + opener + CTA) Pros:
— Finds winning combinations, not just lines
— Bigger lift when you have the volume

Multivariate Cons:
— Needs thousands of sends per cell for significance
— Few cold tools support it cleanly

Verdict: A/B 4.3/5 for most senders, multivariate 3.5/5 unless you're high-volume.

Who it's for: Run plain A/B subject tests if you send under 2,000/week — you'll never hit significance on multivariate. Reserve multivariate for large, repeatable campaigns where 1% lift is real money. Testing four subjects on a 200-lead list is just guessing with extra steps.