Potential Errors When Performing Tests

Potential Errors When Performing Tests is topic 6.7 of AP Statistics, inside Inference for Categorical Data: Proportions. This page works through three real practice questions on it, with the full reasoning behind each credited answer.

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37 questionsStatistical Argumentation100% with a figure
Worked examples

Three real potential errors when performing tests questions

From the practice pool, not the mock papers — each with the reasoning that produces the answer.

100% of them come with a figure. Reading the graph or diagram correctly is most of the work here before any content knowledge applies.

97% test a single AP skill: Statistical Argumentation. That makes this topic unusually predictable to prepare for.

Statistical Argumentation · with figure

Which statement describes a Type I error for false alarm for a lower defect rate?

  1. Aconcluding it is less than 0.06 when the true defect rate is 0.06.correct
  2. BThe P-value or confidence level is the probability that the null hypothesis is true after the sample is observed.
  3. CChanging alpha after seeing the data.
  4. DCorrectly deciding when the true defect rate is 0.06.
  5. EUsing a sample size that is too large.
Why A is correct

Type I error means rejecting a true null hypothesis: concluding it is less than 0.06 when the true defect rate is 0.06.

Type I error for false alarm for a lower defect rate: in the "Which statement describes a Type I error for false alarm for a lower defect rate?" setting, especially false alarm for a lower defect rate; Type I; the true defect rate is 0.06, choose the method that matches the wording of the stem and justify it with context. The professional check is to keep the values 0.06, 1, the type error method, and the final answer choice aligned with Inference for Categorical Data: Proportions.

Statistical Argumentation · with figure

Which statement describes a Type II error for missed increase in late deliveries?

  1. AChanging alpha after seeing the data.
  2. Bfailing to conclude it is greater than 0.10 when the true late-delivery rate is greater than 0.10.correct
  3. CCorrectly deciding when the true late-delivery rate is greater than 0.10.
  4. DUsing a sample size that is too large.
  5. EThe P-value or confidence level is the probability that the null hypothesis is true after the sample is observed.
Why B is correct

Type II error means failing to reject a false null hypothesis: failing to conclude it is greater than 0.10 when the true late-delivery rate is greater than 0.10.

Type II error for missed increase in late deliveries: in the "Which statement describes a Type II error for missed increase in late deliveries?" setting, especially missed increase in late deliveries; Type II; the true late-delivery rate is greater than 0.10, choose the method that matches the wording of the stem and justify it with context. The professional check is to keep the values 0.10, 2, the type error method, and the final answer choice aligned with Inference for Categorical Data: Proportions.

Statistical Argumentation · with figure

Which statement describes a Type I error for false alarm for a lower typo rate?

  1. Aconcluding it is less than 0.06 when the true typo rate is 0.06.correct
  2. BThe P-value or confidence level is the probability that the null hypothesis is true after the sample is observed.
  3. CCorrectly deciding when the true typo rate is 0.06.
  4. DChanging alpha after seeing the data.
  5. EUsing a sample size that is too large.
Why A is correct

Type I error means rejecting a true null hypothesis: concluding it is less than 0.06 when the true typo rate is 0.06.

Type I error for false alarm for a lower typo rate: in the "Which statement describes a Type I error for false alarm for a lower typo rate?" setting, especially false alarm for a lower typo rate; Type I; the true typo rate is 0.06, choose the method that matches the wording of the stem and justify it with context. The professional check is to keep the values 0.06, 1, the type error method, and the final answer choice aligned with Inference for Categorical Data: Proportions.

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Last reviewed 2026-08-28. Topic and unit names follow the College Board course framework. Question counts describe the PrepScore practice bank, not the exam.
Same unit
Concluding a Test for a Population Proportion37 questions

Work potential errors when performing tests until the reasoning is automatic.

Real AP questions with a full explanation on every answer, and a mistake bank that only clears when you get it right.

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