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P-value

Concept​

Terminology

P-value: The probability, under the null hypothesis, that the test statistic is equal to the value that was observed in the data or is even further in the direction of the alternative. Its formal name is the observed significance level.

Result Interpretation​

  • If the p-value is sufficiently large, we say the data is consistent with the null hypothesis and so we "fail to reject the null hypothesis".
  • If the p-value is below some cutoff, we say the data is inconsistent with the null hypothesis, and we "reject the null hypothesis".
    • If a p-value is less than 0.05, the result is said to be statistically significant.
    • If a p-value is less than 0.01, the result is said to be highly statistically significant.

Histogram Visualization​

p-values correspond to the "tail areas" of a histogram, starting at the observed statistic. (to do: add a diagram)

to do: add an example (code + graph) / or link to a coding example