Compared
census.world beside Simile, Aaru and Synthetic Users
Four ways to ask people who are not there. The columns about the others are what their own sites say; where a site says nothing, the cell says so. Checked on 5 September 2026.
| Simile | Aaru | Synthetic Users | census.world | |
|---|---|---|---|---|
| What it says it does | Simulate every decision at scale | Simulate what people will do before you decide | User research, without the users | Ask a calibrated synthetic population, and see who answered and why |
| The population behind the answers | Not declared on the site | Not declared on the site | Personas generated per study | Declared: one profile per US resident, matched to the Census Bureau’s 2025 estimates by state, age, sex, race and origin; ninety attributes from the American Community Survey and public health and civic surveys; every country by age and sex |
| How accuracy is shown | Enterprise quotes and a count of evaluations | A median correlation figure from one partner | A parity range and academic papers | A measured distance from real survey answers per kind of question, printed on every answer; held-out tables per state on the population page |
| Who answered, and why | Not shown on the site | Not shown on the site | Interview transcripts | The people asked with their attributes, and their reasons in their own words, on every answer |
| What is free | Nothing stated | Nothing stated | A trial on request | The first hundred profiles of every question, the gallery of questions, the population page |
| Price | Not published | Not published | Published plans | Not published; full runs arranged through the form on any answer |
| The way in | Run a simulation (a form) | Test your decision (a form) | Book a demo | Ask a question on the front page; the answer arrives in a minute |
The difference in one sentence
census.world starts from a declared population that anyone can inspect, and prints on every answer how far its kind of question tends to sit from real surveys. Try it on a question of your own; the first hundred profiles are free.
Ask a question · How it is built and checked · The population