As a data architect, you can create or edit public reports from the Dashboard in the sandbox. When you create or edit a public report in the sandbox, you can test the reports before you make them available to all users on the live site.
As a data architect, you can also create or edit public reports from the Dashboard on the live site, but only when a sandbox is not active. When you create or edit a public report from the Dashboard, your changes are applied to live the site after you exit edit mode.