The survey question that could affect the accuracy of its results. The United States are due to run their next nationwide census in 2020, but already critics are warning that underfunding and proposed question about citizenship could affect the accuracy of its results. We look at the real life consequences if groups choose not to complete the 2020 census, and ask whether the recent politically charged debate is unusual in its two hundred year history. Presenter: Tim Harford Producer: Kate Lamble Photo: Concerned woman holding a clipboard and a pen Credit: Nicolas McComber/Getty Images