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  2. NaN - Wikipedia

    en.wikipedia.org/wiki/NaN

    In section 6.2 of the old IEEE 754-2008 standard, there are two anomalous functions (the maxNum and minNum functions, which return the maximum and the minimum, respectively, of two operands that are expected to be numbers) that favor numbers — if just one of the operands is a NaN then the value of the other operand is returned.

  3. Missing data - Wikipedia

    en.wikipedia.org/wiki/Missing_data

    Values in a data set are missing completely at random (MCAR) if the events that lead to any particular data-item being missing are independent both of observable variables and of unobservable parameters of interest, and occur entirely at random. [5] When data are MCAR, the analysis performed on the data is unbiased; however, data are rarely MCAR.

  4. IEEE 754 - Wikipedia

    en.wikipedia.org/wiki/IEEE_754

    In general, NaNs will be propagated, i.e. most operations involving a NaN will result in a NaN, although functions that would give some defined result for any given floating-point value will do so for NaNs as well, e.g. NaN ^ 0 = 1. There are two kinds of NaNs: the default quiet NaNs and, optionally, signaling NaNs.

  5. Letter frequency - Wikipedia

    en.wikipedia.org/wiki/Letter_frequency

    The California Job Case was a compartmentalized box for printing in the 19th century, sizes corresponding to the commonality of letters. The frequency of letters in text has been studied for use in cryptanalysis, and frequency analysis in particular, dating back to the Arab mathematician al-Kindi (c. AD 801–873 ), who formally developed the method (the ciphers breakable by this technique go ...

  6. Confusion matrix - Wikipedia

    en.wikipedia.org/wiki/Confusion_matrix

    In predictive analytics, a table of confusion (sometimes also called a confusion matrix) is a table with two rows and two columns that reports the number of true positives, false negatives, false positives, and true negatives. This allows more detailed analysis than simply observing the proportion of correct classifications (accuracy).

  7. Linear congruential generator - Wikipedia

    en.wikipedia.org/wiki/Linear_congruential_generator

    This form may be used with any m, but only works well for m with many repeated prime factors, such as a power of 2; using a computer's word size is the most common choice. If m were a square-free integer , this would only allow a ≡ 1 (mod m ), which makes a very poor PRNG; a selection of possible full-period multipliers is only available when ...

  8. Comparison of numerical-analysis software - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_numerical...

    7.5.1 2 December 2015: $399 (commercial), $199 (academic), Free (student) Proprietary: C/C++ based numerical computing and graphical plotting [1] DADiSP: DSP Development 1984 1987 6.7 B02 17 January 2017: $1995 (commercial), $129 (academic), Free (student) Proprietary: Numeric computations for science and engineering featuring a spreadsheet ...

  9. Nonparametric statistics - Wikipedia

    en.wikipedia.org/wiki/Nonparametric_statistics

    Mann–Whitney U or Wilcoxon rank sum test: tests whether two samples are drawn from the same distribution, as compared to a given alternative hypothesis. McNemar's test: tests whether, in 2 × 2 contingency tables with a dichotomous trait and matched pairs of subjects, row and column marginal frequencies are equal.