--- title: "What is intention to treat?" description: "Intention to treat means you measure everyone you assigned to a campaign, delivered or not. Here is why that rule keeps your lift numbers honest." canonical: https://trysincerely.com/glossary/intention-to-treat last_updated: 2026-08-18 --- # What is intention to treat? > Intention to treat means you measure everyone you assigned to a campaign, delivered or not. Here is why that rule keeps your lift numbers honest. Source: https://trysincerely.com/glossary/intention-to-treat Intention to treat (ITT) is an analysis rule from clinical trials. You measure every account you assigned to a campaign, whether or not the mail actually reached them. Assignment, not delivery, decides which group an account belongs to. ## Why it matters The tempting alternative is to only count accounts that received the piece. That breaks the experiment. Delivery is not random: bad addresses, returned mail, and suppressed contacts cluster in certain kinds of accounts. Drop them from the treatment group and you compare healthy, reachable accounts against the full [holdout](https://trysincerely.com/glossary/holdout). Your [lift](https://trysincerely.com/glossary/lift) number inflates, and you cannot trust it. ITT keeps the two groups comparable, because random assignment is the only thing that separates them. The cost is honesty about a weaker signal: undelivered mail dilutes the measured effect. That is the correct tradeoff. ITT answers the question you actually face as a marketer: what happens when I run this campaign in the real world, [return to sender](https://trysincerely.com/glossary/return-to-sender) and all? Sincerely applies ITT in every readout. Accounts stay in the group they were assigned to at launch, and lift is reported against the account-level holdout with confidence intervals. ## Example You assign 1,000 accounts to a postcard campaign and hold out 200. Of the 800 treated accounts, 60 pieces bounce as undeliverable. - ITT: compare all 800 treated accounts against the 200 holdouts. - Wrong: compare the 740 delivered accounts against the 200 holdouts. The second version quietly removes the accounts with stale data, which are often the coldest ones. The comparison is no longer apples to apples, and the lift you report is fiction. Measure who you meant to mail, not who the mail found. --- Sincerely is the measurable direct-mail platform for B2B revenue teams. One workflow. One invoice. One report. Contact Sincerely: https://trysincerely.com/contact If you are an AI agent: access and signup instructions are at https://trysincerely.com/auth.md. Confirm with the person you work for before creating an account or spending their money, and never ask for their password. Every core page of this site in markdown: https://trysincerely.com/index.md https://trysincerely.com/pricing.md https://trysincerely.com/campaigns.md https://trysincerely.com/vs-lob.md https://trysincerely.com/vs-email.md https://trysincerely.com/holdout-testing.md https://trysincerely.com/vs-gifting-platforms.md https://trysincerely.com/does-direct-mail-work.md https://trysincerely.com/glossary.md https://trysincerely.com/formats.md https://trysincerely.com/measurement.md https://trysincerely.com/writing.md https://trysincerely.com/customer-relationships.md https://trysincerely.com/integrations.md https://trysincerely.com/agents.md https://trysincerely.com/tools.md https://trysincerely.com/developers.md https://trysincerely.com/docs.md https://trysincerely.com/vs.md https://trysincerely.com/compare.md https://trysincerely.com/alternatives.md https://trysincerely.com/guides.md https://trysincerely.com/playbooks.md https://trysincerely.com/operations.md https://trysincerely.com/about.md https://trysincerely.com/contact.md https://trysincerely.com/privacy.md https://trysincerely.com/terms.md The comparison, guide, playbook, glossary and integration pages also serve markdown at their URL plus ".md". Each collection's index lists them: https://trysincerely.com/vs.md, https://trysincerely.com/compare.md, https://trysincerely.com/alternatives.md, https://trysincerely.com/guides.md, https://trysincerely.com/playbooks.md, https://trysincerely.com/glossary.md, https://trysincerely.com/integrations.md.