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  2. Infrared Optical Telescope Array - Wikipedia

    en.wikipedia.org/wiki/Infrared_Optical_Telescope...

    The Infrared Optical Telescope Array (IOTA) was a stellar interferometer array. IOTA began with an agreement in 1988 among five Institutions, the Smithsonian Astrophysical Observatory, Harvard University, the University of Massachusetts Amherst, the University of Wyoming, and MIT/Lincoln Laboratory, to build a two-telescope stellar interferometer for the purpose of making fundamental ...

  3. Standard deviation - Wikipedia

    en.wikipedia.org/wiki/Standard_deviation

    This so-called range rule is useful in sample size estimation, as the range of possible values is easier to estimate than the standard deviation. Other divisors K ( N ) of the range such that s ≈ R / K ( N ) are available for other values of N and for non-normal distributions.

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    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  5. Robust measures of scale - Wikipedia

    en.wikipedia.org/wiki/Robust_measures_of_scale

    Robust measures of scale can be used as estimators of properties of the population, either for parameter estimation or as estimators of their own expected value.. For example, robust estimators of scale are used to estimate the population standard deviation, generally by multiplying by a scale factor to make it an unbiased consistent estimator; see scale parameter: estimation.

  6. x̅ and R chart - Wikipedia

    en.wikipedia.org/wiki/X̅_and_R_chart

    In statistical process control (SPC), the ¯ and R chart is a type of scheme, popularly known as control chart, used to monitor the mean and range of a normally distributed variables simultaneously, when samples are collected at regular intervals from a business or industrial process. [1]

  7. 1951 USAF resolution test chart - Wikipedia

    en.wikipedia.org/.../1951_USAF_resolution_test_chart

    A 1951 USAF resolution test chart is a microscopic optical resolution test device originally defined by the U.S. Air Force MIL-STD-150A standard of 1951. The design provides numerous small target shapes exhibiting a stepped assortment of precise spatial frequency specimens.

  8. 68–95–99.7 rule - Wikipedia

    en.wikipedia.org/wiki/68–95–99.7_rule

    Range Expected fraction of population inside range Expected fraction of population outside range Approx. expected frequency outside range Approx. frequency outside range for daily event μ ± 0.5σ: 0.382 924 922 548 026: 0.6171 = 61.71 % 3 in 5 Four or five times a week μ ± σ: 0.682 689 492 137 086 [5] 0.3173 = 31.73 % 1 in 3 Twice or ...

  9. Unbiased estimation of standard deviation - Wikipedia

    en.wikipedia.org/wiki/Unbiased_estimation_of...

    In statistics and in particular statistical theory, unbiased estimation of a standard deviation is the calculation from a statistical sample of an estimated value of the standard deviation (a measure of statistical dispersion) of a population of values, in such a way that the expected value of the calculation equals the true value.