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  2. p-value - Wikipedia

    en.wikipedia.org/wiki/P-value

    Definition. The p -value is the probability under the null hypothesis of obtaining a real-valued test statistic at least as extreme as the one obtained. Consider an observed test-statistic from unknown distribution . Then the p -value is what the prior probability would be of observing a test-statistic value at least as "extreme" as if null ...

  3. Replication crisis - Wikipedia

    en.wikipedia.org/wiki/Replication_crisis

    The replication crisis[a] is an ongoing methodological crisis in which the results of many scientific studies are difficult or impossible to reproduce. Because the reproducibility of empirical results is an essential part of the scientific method, [2] such failures undermine the credibility of theories building on them and potentially call into ...

  4. Statistical hypothesis test - Wikipedia

    en.wikipedia.org/wiki/Statistical_hypothesis_test

    The p-value is the probability that a test statistic which is at least as extreme as the one obtained would occur under the null hypothesis. At a significance level of 0.05, a fair coin would be expected to (incorrectly) reject the null hypothesis (that it is fair) in 1 out of 20 tests on average.

  5. Statistical significance - Wikipedia

    en.wikipedia.org/wiki/Statistical_significance

    Statistical significance. In statistical hypothesis testing, [1][2] a result has statistical significance when a result at least as "extreme" would be very infrequent if the null hypothesis were true. [3] More precisely, a study's defined significance level, denoted by , is the probability of the study rejecting the null hypothesis, given that ...

  6. One- and two-tailed tests - Wikipedia

    en.wikipedia.org/wiki/One-_and_two-tailed_tests

    The p-value was introduced by Karl Pearson [6] in the Pearson's chi-squared test, where he defined P (original notation) as the probability that the statistic would be at or above a given level. This is a one-tailed definition, and the chi-squared distribution is asymmetric, only assuming positive or zero values, and has only one tail, the ...

  7. Levene's test - Wikipedia

    en.wikipedia.org/wiki/Levene's_test

    If the resulting p-value of Levene's test is less than some significance level (typically 0.05), the obtained differences in sample variances are unlikely to have occurred based on random sampling from a population with equal variances. Thus, the null hypothesis of equal variances is rejected and it is concluded that there is a difference ...

  8. Family-wise error rate - Wikipedia

    en.wikipedia.org/wiki/Family-wise_error_rate

    The procedures of Bonferroni and Holm control the FWER under any dependence structure of the p-values (or equivalently the individual test statistics).Essentially, this is achieved by accommodating a `worst-case' dependence structure (which is close to independence for most practical purposes).

  9. Data dredging - Wikipedia

    en.wikipedia.org/wiki/Data_dredging

    Data dredging (also known as data snooping or p-hacking) [1][a] is the misuse of data analysis to find patterns in data that can be presented as statistically significant, thus dramatically increasing and understating the risk of false positives. This is done by performing many statistical tests on the data and only reporting those that come ...