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A Level synthesis
Lesson 72 of 75
Easy practice

Statistics synthesis

Objective. Build a complete model-test-conclusion chain.

  1. 1. Learn
  2. 2. Worked example
  3. 3. Practice
  4. 4. Feedback
  5. 5. Continue

Learn: the key idea

Statistics synthesis constructs a complete chain from choosing an appropriate probability model for data, through estimating its parameters, to formulating and carrying out a hypothesis test, and finally stating a conclusion in context with appropriate caveats about reliability. This requires linking distribution choice (e.g. binomial, Poisson or normal) to the nature of the data, justified parameter estimation from a sample, correct test statistic calculation, and a conclusion that references the original question. For example, modelling customer arrivals with a Poisson distribution, estimating its mean from sample data, then testing whether the rate has changed, forms one connected statistical argument.

Worked example

A factory assumes faults occur as a Poisson process with mean 4 per day, but a week shows only 14 faults across 7 days. Build a statistics synthesis test of whether the mean rate has decreased, using a mean of 2 faults as a rough comparison threshold from the observed average per day.

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Bar chart of the values 4, 14, 7, 2
  1. 1Sample mean faults per day = 14 ÷ 7 = 2
  2. 2State hypotheses: H0: λ = 4, H1: λ < 4
  3. 3Compare observed mean of 2 against claimed λ = 4: clearly lower
  4. 4Conclusion: the sample suggests the fault rate has decreased from 4 per day, supporting H1

Answer: Sample mean 2 < 4 supports H1: the fault rate has decreased

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Practice

Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.

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Common mistake. Students perform each stage correctly but fail to link them, for example testing a hypothesis using a parameter that does not match the model justified earlier. Always ensure the distribution, the estimated parameter and the test used all refer to the same consistent model.

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