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  2. Homogeneity and heterogeneity (statistics) - Wikipedia

    en.wikipedia.org/wiki/Homogeneity_and...

    In statistics, a sequence of random variables is homoscedastic (/ ˌ h oʊ m oʊ s k ə ˈ d æ s t ɪ k /) if all its random variables have the same finite variance; this is also known as homogeneity of variance. The complementary notion is called heteroscedasticity, also known as heterogeneity of variance.

  3. Scale analysis (statistics) - Wikipedia

    en.wikipedia.org/wiki/Scale_analysis_(statistics)

    The item-total correlation approach is a way of identifying a group of questions whose responses can be combined into a single measure or scale. This is a simple approach that works by ensuring that, when considered across a whole population, responses to the questions in the group tend to vary together and, in particular, that responses to no individual question are poorly related to an ...

  4. Study heterogeneity - Wikipedia

    en.wikipedia.org/wiki/Study_heterogeneity

    The heterogeneity variance is commonly denoted by τ², or the standard deviation (its square root) by τ. Heterogeneity is probably most readily interpretable in terms of τ, as this is the heterogeneity distribution's scale parameter, which is measured in the same units as the overall effect itself. [18]

  5. Homoscedasticity and heteroscedasticity - Wikipedia

    en.wikipedia.org/wiki/Homoscedasticity_and...

    In statistics, a sequence of random variables is homoscedastic (/ ˌ h oʊ m oʊ s k ə ˈ d æ s t ɪ k /) if all its random variables have the same finite variance; this is also known as homogeneity of variance. The complementary notion is called heteroscedasticity, also known as heterogeneity of variance.

  6. Oversampling and undersampling in data analysis - Wikipedia

    en.wikipedia.org/wiki/Oversampling_and_under...

    Oversampling and undersampling are opposite and roughly equivalent techniques. There are also more complex oversampling techniques, including the creation of artificial data points with algorithms like Synthetic minority oversampling technique. [1] [2]

  7. Exogenous and endogenous variables - Wikipedia

    en.wikipedia.org/wiki/Exogenous_and_endogenous...

    An economic variable can be exogenous in some models and endogenous in others. In particular this can happen when one model also serves as a component of a broader model.

  8. Heterogeneity in economics - Wikipedia

    en.wikipedia.org/wiki/Heterogeneity_in_economics

    Krusell and Smith (JPE 1998) permit an arbitrary distribution of wealth but assume all prices and equilibrium variables are approximately functions of the mean or of a few other statistics of that distribution. Algan, Allais, and den Haan (2009) approximate the distribution by a parameterized distributional form at all times.

  9. Difference in differences - Wikipedia

    en.wikipedia.org/wiki/Difference_in_differences

    Difference in differences (DID [1] or DD [2]) is a statistical technique used in econometrics and quantitative research in the social sciences that attempts to mimic an experimental research design using observational study data, by studying the differential effect of a treatment on a 'treatment group' versus a 'control group' in a natural experiment. [3]