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NOTE Beetles: dose, LD50 and a test for curvature: captions match the on-screen steps.

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Step 1 of 7. Six case studies from MAST90139, refitted live in your browser and checked against R.

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Step 2 of 7. Beetle mortality: a binomial GLM with a logit link, 481 beetles at 8 doses.

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Step 3 of 7. Drag the dose: P(killed) and its 95% interval are refitted at every step.

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Step 4 of 7. LD50 = 1.7712, delta-method 95% CI 1.7636 to 1.7788.

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Step 5 of 7. Switch to a quadratic predictor: the curve bends and the residual pattern goes.

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Step 6 of 7. Likelihood-ratio test: the quadratic term lowers the deviance by 8.526 on 1 df (p = 0.0035).

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Step 7 of 7. Model checks: four interval methods agree, but the mean model moves the LD50 more.