science

Up-and-down procedure

Up-and-down procedure is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Up-and-down procedure rather than just read about it. In short: Up-and-down procedure (or method) for toxicology tests in medicine is an alternative to the LD50 test, in which animals are used for acute toxicity testing. It requires fewer animals to achieve similar accuracy as the LD50 test because animals are dosed one at a time.

Key takeaways

Up-and-down procedure belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Up-and-down procedure to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Up-and-down procedure from memory before moving on to harder problems.

Reference excerpt

Up-and-down procedure (or method) for toxicology tests in medicine is an alternative to the LD50 test, in which animals are used for acute toxicity testing. It requires fewer animals to achieve similar accuracy as the LD50 test because animals are dosed one at a time. If the first animal survives, the dose for the next animal is increased; if it dies, the dose is decreased. It is usual to observe each animal for 1 or 2 days before dosing the next animal, however, surviving animals should be monitored for 7 days in case of delayed death. The up-and-down method is not recommended where deaths beyond 2 days are the norm. The US EPA provides a statistical program to calculate the oral LD50 and 95% Confidence Limits called AOT425StatPgm. This program will notify the user when a stopping criteria has been met, while being able to generate statistically valid LD50, using fewer animals. The U.S. Food and Drug Administration has begun to approve non-animal alternatives.

References

Further reading Dixon, W. J. (1965). "The Up-and-Down Method for Small Samples". Journal of the American Statistical Association. 60 (312): 967–978. doi:10.1080/01621459.1965.10480843. JSTOR 2283398. Brownlee, K. A.; Hodges, J. L.; Rosenblatt, Murray (1953). "The Up-and-Down Method with Small Samples". Journal of the American Statistical Association. 48 (262): 262–277. doi:10.1080/01621459.1953.10483472. JSTOR 2281287. Dixon, W.J. (March 1991). "Staircase bioassay: The up-and-down method". Neuroscience & Biobehavioral Reviews. 15 (1): 47–50. doi:10.1016/s0149-7634(05)80090-9. PMID 2052197. S2CID 39936998.

Worked examples

Example 1 — a first encounter with Up-and-down procedure

Start with the simplest possible case. Write down what Up-and-down procedure claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Up-and-down procedure before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Up-and-down procedure ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Up-and-down procedure

In research: Up-and-down procedure appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Up-and-down procedure in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Up-and-down procedure is common in secondary-school and first-year university syllabi. It links to neighbouring topics Toxicology stubs, Toxicology tests, so understanding it makes those chapters shorter.
In everyday life: Look for Up-and-down procedure outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Up-and-down procedure in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Up-and-down procedure means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Up-and-down procedure out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Up-and-down procedure in simple terms?

Why does Up-and-down procedure matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Up-and-down procedure?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Up-and-down procedure.