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  2. Standard normal table - Wikipedia

    en.wikipedia.org/wiki/Standard_normal_table

    In statistics, a standard normal table, also called the unit normal table or Z table, [1] is a mathematical table for the values of Φ, the cumulative distribution function of the normal distribution.

  3. 68–95–99.7 rule - Wikipedia

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

    The next step is standardizing (dividing by the population standard deviation), if the population parameters are known, or studentizing (dividing by an estimate of the standard deviation), if the parameters are unknown and only estimated.

  4. Standard score - Wikipedia

    en.wikipedia.org/wiki/Standard_score

    Comparison of the various grading methods in a normal distribution, including: standard deviations, cumulative percentages, percentile equivalents, z-scores, T-scores. In statistics, the standard score is the number of standard deviations by which the value of a raw score (i.e., an observed value or data point) is above or below the mean value of what is being observed or measured.

  5. Symbolab - Wikipedia

    en.wikipedia.org/wiki/Symbolab

    Symbolab is an answer engine [1] that provides step-by-step solutions to mathematical problems in a range of subjects. [2] It was originally developed by Israeli start-up company EqsQuest Ltd., under whom it was released for public use in 2011. In 2020, the company was acquired by American educational technology website Course Hero. [3] [4]

  6. Z-test - Wikipedia

    en.wikipedia.org/wiki/Z-test

    How to perform a Z test when T is a statistic that is approximately normally distributed under the null hypothesis is as follows: . First, estimate the expected value μ of T under the null hypothesis, and obtain an estimate s of the standard deviation of T.

  7. Normal score - Wikipedia

    en.wikipedia.org/wiki/Normal_score

    The term normal score is used with two different meanings in statistics. One of them relates to creating a single value which can be treated as if it had arisen from a standard normal distribution (zero mean, unit variance). The second one relates to assigning alternative values to data points within a dataset, with the broad intention of ...

  8. 97.5th percentile point - Wikipedia

    en.wikipedia.org/wiki/97.5th_percentile_point

    95% of the area under the normal distribution lies within 1.96 standard deviations away from the mean.. In probability and statistics, the 97.5th percentile point of the standard normal distribution is a number commonly used for statistical calculations.

  9. Elo rating system - Wikipedia

    en.wikipedia.org/wiki/Elo_rating_system

    The development of the Percentage Expectancy Table (table 2.11) is described in more detail by Elo as follows: [15] The normal probabilities may be taken directly from the standard tables of the areas under the normal curve when the difference in rating is expressed as a z score.