Visualize three test types: z-test for proportions, t-test for means, and χ²-test. Adjust the test statistic parameters, choose α (0.01/0.05/0.10), and select one- or two-tailed Hₐ. The rejection region (red), p-value shading, and critical values update live. Decision badge shows REJECT H₀ or FAIL TO REJECT.