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  2. Pearson's chi-squared test - Wikipedia

    en.wikipedia.org/wiki/Pearson's_chi-squared_test

    For the test of independence, also known as the test of homogeneity, a chi-squared probability of less than or equal to 0.05 (or the chi-squared statistic being at or larger than the 0.05 critical point) is commonly interpreted by applied workers as justification for rejecting the null hypothesis that the row variable is independent of the ...

  3. Rounding - Wikipedia

    en.wikipedia.org/wiki/Rounding

    Whether a value x ∈ (a, b) rounds to a or b depends upon whether the squared value x 2 is greater than or less than the product ab. The value 165 rounds to 180 in the resistors example because 165 2 = 27225 is greater than 150 × 180 = 27000 .

  4. Benford's law - Wikipedia

    en.wikipedia.org/wiki/Benford's_law

    The interval [log 1, log 2] is much wider than the interval [log 9, log 10] (0.30 and 0.05 respectively); therefore if log x is uniformly and randomly distributed, it is much more likely to fall into the wider interval than the narrower interval, i.e. more likely to start with 1 than with 9; the probabilities are proportional to the interval ...

  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. Sensitivity and specificity - Wikipedia

    en.wikipedia.org/wiki/Sensitivity_and_specificity

    Unlike the Specificity vs Sensitivity tradeoff, these measures are both independent of the number of true negatives, which is generally unknown and much larger than the actual numbers of relevant and retrieved documents. This assumption of very large numbers of true negatives versus positives is rare in other applications. [13]

  7. Standard deviation - Wikipedia

    en.wikipedia.org/wiki/Standard_deviation

    The larger the variance, the greater risk the security carries. Finding the square root of this variance will give the standard deviation of the investment tool in question. Financial time series are known to be non-stationary series, whereas the statistical calculations above, such as standard deviation, apply only to stationary series.

  8. Decibel - Wikipedia

    en.wikipedia.org/wiki/Decibel

    The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...

  9. Angular diameter - Wikipedia

    en.wikipedia.org/wiki/Angular_diameter

    Appearing about three to four times larger than the Moon in Earth's sky The Sun in the sky of Mercury: 1.15° - 1.76° [13] Orion Nebula: 1°5 ′ by 1° Width of little finger with arm stretched out 1° 17.5 meter at 1 km distance The Sun in the sky of Venus: 0.7° [13] [14] Io (as seen from the “surface” of Jupiter) 35’ 35” Moon