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Biostatistics & Research · single question

Which of the following statements is true about p-values?

  1. It is the chance of getting an observed effect given the null hypothesis was false
  2. It is the probability of the sample data arising by chance if the null hypothesis were true
  3. It represents the probability of Type I error
  4. It is calculated by taking the square root of the variance
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Correct answer: A. It is the chance of getting an observed effect given the null hypothesis was false

  • A. Correct. The p-value is the probability of obtaining results at least as extreme as observed, assuming the null hypothesis is true. p < 0.05 means <5% chance the results arose by random chance alone.
  • B. Incorrect. Square root of variance is the standard deviation — a measure of variability, not a p-value.
  • C. Incorrect. The p-value assumes the null hypothesis IS true, not false.
  • D. Incorrect. P-value is related to but not identical to the Type I error rate (alpha).

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