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  2. Quartile - Wikipedia

    en.wikipedia.org/wiki/Quartile

    Since quartiles divide the number of data points evenly, the range is generally not the same between adjacent quartiles (i.e. usually (Q 3 - Q 2) ≠ (Q 2 - Q 1)). Interquartile range (IQR) is defined as the difference between the 75th and 25th percentiles or Q 3 - Q 1 .

  3. Sample size determination - Wikipedia

    en.wikipedia.org/wiki/Sample_size_determination

    The table shown on the right can be used in a two-sample t-test to estimate the sample sizes of an experimental group and a control group that are of equal size, that is, the total number of individuals in the trial is twice that of the number given, and the desired significance level is 0.05. [4]

  4. Expected value - Wikipedia

    en.wikipedia.org/wiki/Expected_value

    The idea of the expected value originated in the middle of the 17th century from the study of the so-called problem of points, which seeks to divide the stakes in a fair way between two players, who have to end their game before it is properly finished. [4] This problem had been debated for centuries.

  5. Quantile - Wikipedia

    en.wikipedia.org/wiki/Quantile

    The second quartile value (same as the median) is determined by 11×(2/4) = 5.5, which rounds up to 6. Therefore, 6 is the rank in the population (from least to greatest values) at which approximately 2/4 of the values are less than the value of the second quartile (or median). The sixth value in the population is 9. 9 Third quartile

  6. Chi-squared distribution - Wikipedia

    en.wikipedia.org/wiki/Chi-squared_distribution

    Suppose that is a random variable sampled from the standard normal distribution, where the mean is and the variance is : (,). Now, consider the random variable X = Z 2 {\displaystyle X=Z^{2}} . The distribution of the random variable X {\displaystyle X} is an example of a chi-squared distribution: X ∼ χ 1 2 {\displaystyle \ X\ \sim \ \chi ...

  7. Probability distribution - Wikipedia

    en.wikipedia.org/wiki/Probability_distribution

    A real-valued discrete random variable can equivalently be defined as a random variable whose cumulative distribution function increases only by jump discontinuities—that is, its cdf increases only where it "jumps" to a higher value, and is constant in intervals without jumps. The points where jumps occur are precisely the values which the ...

  8. Effect size - Wikipedia

    en.wikipedia.org/wiki/Effect_size

    In statistics, an effect size is a value measuring the strength of the relationship between two variables in a population, or a sample-based estimate of that quantity. It can refer to the value of a statistic calculated from a sample of data, the value of one parameter for a hypothetical population, or to the equation that operationalizes how statistics or parameters lead to the effect size ...

  9. Odds - Wikipedia

    en.wikipedia.org/wiki/Odds

    Odds of 4/1 would imply that the bettor stands to make a £400 profit on a £100 stake. If the odds are 1/4, the bettor will make £25 on a £100 stake. In either case, having won, the bettor always receives the original stake back; so if the odds are 4/1 the bettor receives a total of £500 (£400 plus the original £100).