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  2. Grouped data - Wikipedia

    en.wikipedia.org/wiki/Grouped_data

    In this formula, x refers to the midpoint of the class intervals, and f is the class frequency. Note that the result of this will be different from the sample mean of the ungrouped data. The mean for the grouped data in the above example, can be calculated as follows:

  3. Error function - Wikipedia

    en.wikipedia.org/wiki/Error_function

    Given a random variable X ~ Norm[μ,σ] (a normal distribution with mean μ and standard deviation σ) and a constant L > μ, it can be shown via integration by substitution: [] = + ⁡ ⁡ (()) where A and B are certain numeric constants.

  4. Errors-in-variables model - Wikipedia

    en.wikipedia.org/wiki/Errors-in-variables_model

    Linear errors-in-variables models were studied first, probably because linear models were so widely used and they are easier than non-linear ones. Unlike standard least squares regression (OLS), extending errors in variables regression (EiV) from the simple to the multivariable case is not straightforward, unless one treats all variables in the same way i.e. assume equal reliability.

  5. Fixed effects model - Wikipedia

    en.wikipedia.org/wiki/Fixed_effects_model

    The group means could be modeled as fixed or random effects for each grouping. In a fixed effects model each group mean is a group-specific fixed quantity. In panel data where longitudinal observations exist for the same subject, fixed effects represent the subject-specific means.

  6. Proportionate reduction of error - Wikipedia

    en.wikipedia.org/wiki/Proportionate_reduction_of...

    The summary statistics is particularly useful and popular when used to evaluate models where the dependent variable is binary, taking on values {0,1}. Example [ edit ]

  7. Mean squared error - Wikipedia

    en.wikipedia.org/wiki/Mean_squared_error

    The MSE either assesses the quality of a predictor (i.e., a function mapping arbitrary inputs to a sample of values of some random variable), or of an estimator (i.e., a mathematical function mapping a sample of data to an estimate of a parameter of the population from which the data is sampled).

  8. Variance decomposition of forecast errors - Wikipedia

    en.wikipedia.org/wiki/Variance_decomposition_of...

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  9. Sheppard's correction - Wikipedia

    en.wikipedia.org/wiki/Sheppard's_correction

    The cumulants of the sum of the grouped variable and the uniform variable are the sums of the cumulants. As odd cumulants of a uniform distribution are zero; only even moments are affected. As odd cumulants of a uniform distribution are zero; only even moments are affected.