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  2. Data cleansing - Wikipedia

    en.wikipedia.org/wiki/Data_cleansing

    Data-Type Constraints: values in a particular column must be of a particular data type, e.g., Boolean, numeric (integer or real), date. Range Constraints: typically, numbers or dates should fall within a certain range. That is, they have minimum and/or maximum permissible values. Mandatory Constraints: Certain columns cannot be empty.

  3. Pivot table - Wikipedia

    en.wikipedia.org/wiki/Pivot_table

    Row labels are used to apply a filter to one or more rows that have to be shown in the pivot table. For instance, if the "Salesperson" field is dragged on this area then the other output table constructed will have values from the column "Salesperson", i.e., one will have a number of rows equal to the number of "Sales Person". There will also ...

  4. Hash function - Wikipedia

    en.wikipedia.org/wiki/Hash_function

    The value a is an appropriately chosen value that should be relatively prime to W; it should be large, [clarification needed] and its binary representation a random mix [clarification needed] of 1s and 0s. An important practical special case occurs when W = 2 w and M = 2 m are powers of 2 and w is the machine word size.

  5. k-means clustering - Wikipedia

    en.wikipedia.org/wiki/K-means_clustering

    k-means clustering is a method of vector quantization, originally from signal processing, that aims to partition n observations into k clusters in which each observation belongs to the cluster with the nearest mean (cluster centers or cluster centroid), serving as a prototype of the cluster.

  6. Logistic regression - Wikipedia

    en.wikipedia.org/wiki/Logistic_regression

    Logistic regression is used in various fields, including machine learning, most medical fields, and social sciences. For example, the Trauma and Injury Severity Score (), which is widely used to predict mortality in injured patients, was originally developed by Boyd et al. using logistic regression. [6]

  7. PANDAS - Wikipedia

    en.wikipedia.org/wiki/PANDAS

    A possible relationship between PANDAS and other early-onset conditions. [24]PANDAS is hypothesized to be an autoimmune disorder that results in a variable combination of tics, obsessions, compulsions, and other symptoms with sudden or abrupt onset that may be severe enough to qualify for diagnoses such as chronic tic disorder, OCD, and TS.

  8. Ordinary least squares - Wikipedia

    en.wikipedia.org/wiki/Ordinary_least_squares

    In statistics, ordinary least squares (OLS) is a type of linear least squares method for choosing the unknown parameters in a linear regression model (with fixed level-one [clarification needed] effects of a linear function of a set of explanatory variables) by the principle of least squares: minimizing the sum of the squares of the differences between the observed dependent variable (values ...

  9. Normal distribution - Wikipedia

    en.wikipedia.org/wiki/Normal_distribution

    About 68% of values drawn from a normal distribution are within one standard deviation σ from the mean; about 95% of the values lie within two standard deviations; and about 99.7% are within three standard deviations. [8] This fact is known as the 68–95–99.7 (empirical) rule, or the 3-sigma rule.