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  2. Standard normal table - Wikipedia

    en.wikipedia.org/wiki/Standard_normal_table

    Example: To find 0.69, one would look down the rows to find 0.6 and then across the columns to 0.09 which would yield a probability of 0.25490 for a cumulative from mean table or 0.75490 from a cumulative table. To find a negative value such as -0.83, one could use a cumulative table for negative z-values [3] which yield a probability of 0.20327.

  3. 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.

  4. Z-test - Wikipedia

    en.wikipedia.org/wiki/Z-test

    Because of the central limit theorem, many test statistics are approximately normally distributed for large samples.Therefore, many statistical tests can be conveniently performed as approximate Z-tests if the sample size is large or the population variance is known.

  5. Normal curve equivalent - Wikipedia

    en.wikipedia.org/wiki/Normal_curve_equivalent

    In educational statistics, a normal curve equivalent (NCE), developed for the United States Department of Education by the RMC Research Corporation, [1] is a way of normalizing scores received on a test into a 0-100 scale similar to a percentile rank, but preserving the valuable equal-interval properties of a z-score.

  6. List of probability distributions - Wikipedia

    en.wikipedia.org/wiki/List_of_probability...

    It is ubiquitous in nature and statistics due to the central limit theorem: every variable that can be modelled as a sum of many small independent, identically distributed variables with finite mean and variance is approximately normal. The normal-exponential-gamma distribution; The normal-inverse Gaussian distribution

  7. Normality test - Wikipedia

    en.wikipedia.org/wiki/Normality_test

    Simple back-of-the-envelope test takes the sample maximum and minimum and computes their z-score, or more properly t-statistic (number of sample standard deviations that a sample is above or below the sample mean), and compares it to the 68–95–99.7 rule: if one has a 3σ event (properly, a 3s event) and substantially fewer than 300 samples, or a 4s event and substantially fewer than 15,000 ...

  8. Prisoners of Profit - The Huffington Post

    projects.huffingtonpost.com/prisoners-of-profit?...

    In 2001, an 18-year-old committed to a Texas boot camp operated by one of Slattery’s previous companies, Correctional Services Corp., came down with pneumonia and pleaded to see a doctor as he struggled to breathe.

  9. Normal distribution - Wikipedia

    en.wikipedia.org/wiki/Normal_distribution

    Rectified Gaussian distribution a rectified version of normal distribution with all the negative elements reset to 0 Complex normal distribution deals with the complex normal vectors. A complex vector X ∈ C k is said to be normal if both its real and imaginary components jointly possess a 2 k -dimensional multivariate normal distribution.