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  2. Aggregate function - Wikipedia

    en.wikipedia.org/wiki/Aggregate_function

    The input and output domains may be the same, such as for SUM, or may be different, such as for COUNT. Aggregate functions occur commonly in numerous programming languages, in spreadsheets, and in relational algebra. The listagg function, as defined in the SQL:2016 standard [2] aggregates data from multiple rows into a single concatenated string.

  3. Aggregate (data warehouse) - Wikipedia

    en.wikipedia.org/wiki/Aggregate_(data_warehouse)

    An aggregate is a type of summary used in dimensional models of data warehouses to shorten the time it takes to provide answers to typical queries on large sets of data. The reason why aggregates can make such a dramatic increase in the performance of a data warehouse is the reduction of the number of rows to be accessed when responding to a query.

  4. Point-biserial correlation coefficient - Wikipedia

    en.wikipedia.org/wiki/Point-biserial_correlation...

    Further, n 1 is the number of data points in group 1, n 0 is the number of data points in group 2 and n is the total sample size. This formula is a computational formula that has been derived from the formula for r XY in order to reduce steps in the calculation; it is easier to compute than r XY. There is an equivalent formula that uses s n−1:

  5. Aggregate data - Wikipedia

    en.wikipedia.org/wiki/Aggregate_data

    Aggregate data are also used for medical and educational purposes. Aggregate data is widely used, but it also has some limitations, including drawing inaccurate inferences and false conclusions which is also termed ‘ecological fallacy’. [3] ‘Ecological fallacy’ means that it is invalid for users to draw conclusions on the ecological ...

  6. Row and column spaces - Wikipedia

    en.wikipedia.org/wiki/Row_and_column_spaces

    then the row vectors are r 1 = [1, 0, 2] and r 2 = [0, 1, 0]. ... The pivots indicate that the first two columns of A T form a basis of the column space of A T.

  7. Area density - Wikipedia

    en.wikipedia.org/wiki/Area_density

    A special type of area density is called column density (also columnar mass density or simply column density), denoted ρ A or σ. It is the mass of substance per unit area integrated along a path; [ 1 ] It is obtained integrating volumetric density ρ {\displaystyle \rho } over a column: [ 2 ] σ = ∫ ρ d s . {\displaystyle \sigma =\int \rho ...

  8. 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]

  9. List of integer sequences - Wikipedia

    en.wikipedia.org/wiki/List_of_integer_sequences

    The n th term describes the length of the n th run ... (n − 1) which is a unique sum of two distinct earlier terms ... Sum of numbers in any row, column, ...