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  2. Slide rule scale - Wikipedia

    en.wikipedia.org/wiki/Slide_rule_scale

    scale type range of x range on scale numerical range (approx) Increase / decrease [note 6] comment C: x: fundamental scale: 1 to 10: 1 to 10: 1 to 10: increase: On slider D: x: fundamental scale used with C: 1 to 10: 1 to 10: 1 to 10: increase: On body A: x 2: square: 1 to 10: 1 to 100: 1 to 100: increase: On body. Two log cycles at half the ...

  3. Chi-squared distribution - Wikipedia

    en.wikipedia.org/wiki/Chi-squared_distribution

    Because the square of a standard normal distribution is the chi-squared distribution with one degree of freedom, the probability of a result such as 1 heads in 10 trials can be approximated either by using the normal distribution directly, or the chi-squared distribution for the normalised, squared difference between observed and expected value.

  4. Normal distribution - Wikipedia

    en.wikipedia.org/wiki/Normal_distribution

    A vector X ∈ R k is multivariate-normally distributed if any linear combination of its components Σ k j=1 a j X j has a (univariate) normal distribution. The variance of X is a k×k symmetric positive-definite matrix V. The multivariate normal distribution is a special case of the elliptical distributions.

  5. Log-normal distribution - Wikipedia

    en.wikipedia.org/wiki/Log-normal_distribution

    Thus, if the random variable X is log-normally distributed, then Y = ln(X) has a normal distribution. [2] [3] Equivalently, if Y has a normal distribution, then the exponential function of Y, X = exp(Y), has a log-normal distribution. A random variable which is log-normally distributed takes only positive real values.

  6. Relationships among probability distributions - Wikipedia

    en.wikipedia.org/wiki/Relationships_among...

    If X and Y are independent standard normal random variables, X/Y is a Cauchy (0,1) random variable. If X 1 and X 2 are independent chi-squared random variables with ν 1 and ν 2 degrees of freedom respectively, then (X 1 /ν 1)/(X 2 /ν 2) is an F(ν 1, ν 2) random variable.

  7. Pearson's chi-squared test - Wikipedia

    en.wikipedia.org/wiki/Pearson's_chi-squared_test

    For the test of independence, also known as the test of homogeneity, a chi-squared probability of less than or equal to 0.05 (or the chi-squared statistic being at or larger than the 0.05 critical point) is commonly interpreted by applied workers as justification for rejecting the null hypothesis that the row variable is independent of the ...

  8. Chi-squared test - Wikipedia

    en.wikipedia.org/wiki/Chi-squared_test

    A chi-squared test (also chi-square or χ 2 test) is a statistical hypothesis test used in the analysis of contingency tables when the sample sizes are large. In simpler terms, this test is primarily used to examine whether two categorical variables ( two dimensions of the contingency table ) are independent in influencing the test statistic ...

  9. Noncentral chi-squared distribution - Wikipedia

    en.wikipedia.org/wiki/Noncentral_chi-squared...

    From this representation, the noncentral chi-squared distribution is seen to be a Poisson-weighted mixture of central chi-squared distributions. Suppose that a random variable J has a Poisson distribution with mean λ / 2 {\displaystyle \lambda /2} , and the conditional distribution of Z given J = i is chi-squared with k + 2 i degrees of freedom.