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  2. Inequality (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Inequality_(mathematics)

    The same is true for not less than, . The notation a ≠ b means that a is not equal to b; this inequation sometimes is considered a form of strict inequality. [4] It does not say that one is greater than the other; it does not even require a and b to be member of an ordered set. In engineering sciences, less formal use of the notation is to ...

  3. Coefficient of determination - Wikipedia

    en.wikipedia.org/wiki/Coefficient_of_determination

    If equation 1 of Kvålseth [12] is used (this is the equation used most often), R 2 can be less than zero. If equation 2 of Kvålseth is used, R 2 can be greater than one. In all instances where R 2 is used, the predictors are calculated by ordinary least-squares regression: that is, by minimizing SS res .

  4. Spearman's rank correlation coefficient - Wikipedia

    en.wikipedia.org/wiki/Spearman's_rank_correlation...

    One approach to test whether an observed value of ρ is significantly different from zero (r will always maintain −1 ≤ r ≤ 1) is to calculate the probability that it would be greater than or equal to the observed r, given the null hypothesis, by using a permutation test. An advantage of this approach is that it automatically takes into ...

  5. Probability density function - Wikipedia

    en.wikipedia.org/wiki/Probability_density_function

    For example, the probability that it lives longer than 5 hours, but shorter than (5 hours + 1 nanosecond), is (2 hour −1)×(1 nanosecond) ≈ 6 × 10 −13 (using the unit conversion 3.6 × 10 12 nanoseconds = 1 hour). There is a probability density function f with f(5 hours) = 2 hour −1.

  6. Skewness - Wikipedia

    en.wikipedia.org/wiki/Skewness

    In the older notion of nonparametric skew, defined as () /, where is the mean, is the median, and is the standard deviation, the skewness is defined in terms of this relationship: positive/right nonparametric skew means the mean is greater than (to the right of) the median, while negative/left nonparametric skew means the mean is less than (to ...

  7. Relative change - Wikipedia

    en.wikipedia.org/wiki/Relative_change

    A percentage change is a way to express a change in a variable. It represents the relative change between the old value and the new one. [6]For example, if a house is worth $100,000 today and the year after its value goes up to $110,000, the percentage change of its value can be expressed as = = %.

  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. Index of dispersion - Wikipedia

    en.wikipedia.org/wiki/Index_of_dispersion

    In probability theory and statistics, the index of dispersion, [1] dispersion index, coefficient of dispersion, relative variance, or variance-to-mean ratio (VMR), like the coefficient of variation, is a normalized measure of the dispersion of a probability distribution: it is a measure used to quantify whether a set of observed occurrences are clustered or dispersed compared to a standard ...