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  2. x̅ and R chart - Wikipedia

    en.wikipedia.org/wiki/X̅_and_R_chart

    The "chart" actually consists of a pair of charts: One to monitor the process standard deviation (as approximated by the sample moving range) and another to monitor the process mean, as is done with the ¯ and s and individuals control charts.

  3. X-ray diffraction - Wikipedia

    en.wikipedia.org/wiki/X-ray_diffraction

    Barkla created the x-ray notation for sharp spectral lines, noting in 1909 two separate energies, at first, naming them "A" and "B" and, supposing that there may be lines prior to "A", he started an alphabet numbering beginning with "K." [2] [3] Single-slit experiments in the laboratory of Arnold Sommerfeld suggested that X-rays had a ...

  4. x̅ and s chart - Wikipedia

    en.wikipedia.org/wiki/X̅_and_s_chart

    In statistical quality control, the ¯ and s chart is a type of control chart used to monitor variables data when samples are collected at regular intervals from a business or industrial process. [1] This is connected to traditional statistical quality control (SQC) and statistical process control (SPC).

  5. Standard deviation - Wikipedia

    en.wikipedia.org/wiki/Standard_deviation

    A little algebra shows that the distance between P and M (which is the same as the orthogonal distance between P and the line L) (¯) is equal to the standard deviation of the vector (x 1, x 2, x 3), multiplied by the square root of the number of dimensions of the vector (3 in this case).

  6. Shewhart individuals control chart - Wikipedia

    en.wikipedia.org/wiki/Shewhart_individuals...

    The "chart" actually consists of a pair of charts: one, the individuals chart, displays the individual measured values; the other, the moving range chart, displays the difference from one point to the next.

  7. Reduced chi-squared statistic - Wikipedia

    en.wikipedia.org/wiki/Reduced_chi-squared_statistic

    The standard deviation is the square root of the variance. When individual determinations of an age are not of equal significance, it is better to use a weighted mean to obtain an "average" age, as follows: x ¯ ∗ = ∑ i = 1 N w i x i ∑ i = 1 N w i . {\displaystyle {\overline {x}}^{*}={\frac {\sum _{i=1}^{N}w_{i}x_{i}}{\sum _{i=1}^{N}w_{i}}}.}

  8. Error bar - Wikipedia

    en.wikipedia.org/wiki/Error_bar

    This statistics -related article is a stub. You can help Wikipedia by expanding it.

  9. R-factor (crystallography) - Wikipedia

    en.wikipedia.org/wiki/R-factor_(crystallography)

    Crystallographers also use the Free R-Factor [3] to assess possible overmodeling of the data. R F r e e {\displaystyle R_{Free}} is computed according to the same formula given above, but on a small, random sample of data that are set aside for the purpose and never included in the refinement.