Introduction to the Anderson-Darling Test (short) - Engineering Statistics

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https://www.youtube.com/watch?v=Rgkj9tT7sKM

الملخص

TLDRThe Anderson-Darling goodness of fit test is a hypothesis test used to assess whether a dataset follows a specified distribution. Unlike some tests, it is not limited to assessing normal distribution and can be applied to various distributions. The test works by calculating a weighted comparison of each measurement's probability against expected values, with an emphasis on the tails of the distribution. This approach makes it more sensitive to deviations, particularly in the tails. The process involves determining a test statistic, which is then used to compute a P-value through piecewise functions. Comparing this P-value against a critical value helps in deciding if the data adheres to the specified distribution.

الوجبات الجاهزة

  • 📊 The Anderson-Darling test checks if data follows a specified distribution.
  • ❗ It's not limited to the normal distribution.
  • 🔍 It gives more weight to the tails of the distribution.
  • 📈 Uses weighted z-scores to compare expected and actual values.
  • ⚙️ Tail weight sensitivity makes it more selective.
  • 🔣 Calculates P-value using test statistics and piecewise functions.
  • 💡 Helps decide if data aligns with a given distribution.
  • 🔬 Frequently used in engineering.
  • 📉 More emphasis on tail discrepancies than other tests.
  • 💼 Useful for multiple distributions.

الجدول الزمني

  • 00:00:00 - 00:02:24

    The Anderson-Darling test is a versatile goodness-of-fit test used in engineering to assess whether data follows a specified distribution, not limited to just the normal distribution. The test involves a hypothesis: the null hypothesis claims that the data conforms to the specified distribution, while the alternative suggests otherwise. The test calculates a weighted comparison of z-scores, emphasizing discrepancies, particularly in the tails of the distribution. This trait renders the Anderson-Darling test particularly sensitive, often making it the first choice for normality testing. The process involves summing weighted values and scaling them by the sample size to get the test statistic, which is then used to derive a p-value through piecewise functions. Comparing the p-value to a critical threshold helps determine if the data fits the specified distribution.

الخريطة الذهنية

Mind Map

الأسئلة الشائعة

  • What does the Anderson-Darling test assess?

    The Anderson-Darling test assesses whether data follows a specified distribution, not limited to normal distribution.

  • What is the null hypothesis in the Anderson-Darling test?

    The null hypothesis is that the data follows the specified distribution.

  • What types of distributions can the Anderson-Darling test be used for?

    The Anderson-Darling test can be used for multiple distributions, not just the normal distribution.

  • How does the Anderson-Darling test work?

    It calculates a weighted comparison of the probability of each measurement's z-score to determine discrepancies between actual measurements and expected values from the distribution.

  • Why is the Anderson-Darling test considered selective?

    Because it puts a higher weight on the tails of the distribution, making it more sensitive to deviations in heavy tails.

  • What does the test statistic represent in the Anderson-Darling test?

    The test statistic represents a scaled sum of weighted values derived from comparing sample z-scores to expected z-scores.

  • How is the P-value calculated in the Anderson-Darling test?

    The P-value is calculated using a set of piecewise functions based on the Anderson-Darling test statistic.

  • What is the significance of comparing the P-value with a critical value?

    It helps determine whether the data follows the specified distribution or not based on whether the P-value is less than the critical value.

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الترجمات
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التمرير التلقائي:
  • 00:00:00
    so the Anderson darling goodness of fit
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    test is a commonly used test in
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    engineering because it's not just for
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    the normal distribution the Anderson
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    darling test is a goodness of fit test
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    and like most goodness of fit tests it's
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    a hypothesis test for the Anderson
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    darling test the null hypothesis is that
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    the data followed the specified
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    distribution the alternative hypothesis
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    is that the data do not follow the
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    specified
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    distribution so you'll notice it's
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    specified
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    distribution and specified distribution
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    not the normal distribution we'll get
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    into that later but that's really
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    because the Anderson darling test can be
  • 00:00:39
    used for multiple
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    distributions okay but how does it work
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    well the Anderson darling goodness to
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    fit test calculates a weighted
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    comparison of the probability of each
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    measurement's zcore to determine the
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    discrepancy of the actual measurements
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    and expected values from the
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    distribution so that is all a lot of
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    words there and what it's really saying
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    is that it's a weighted comparison of
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    How likely each zcore is when you
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    compare it to the expected zc
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    scores and by weighted we just mean that
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    different um zc scores in different
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    locations um get uh higher priority when
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    it comes to calculating the Anderson
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    darling test statistic so for the
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    Anderson darling test statistic um
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    you'll find that it's usually the first
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    normality test
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    because it puts a higher weight on the
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    Tails which means that if you have
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    heavier Tails um it's going to affect um
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    whether your you pass your and can
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    assume normality or not so it's going to
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    be a little bit more selective than
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    other tests that's not what today's
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    video is about today's video is really
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    about the math behind it but in order to
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    understand the math we have to
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    understand what we're trying to do so
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    once we have these weighted values we
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    sum them and scale them using the number
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    of samples to calculate our Anderson
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    darling test
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    statistic then once we have the Anderson
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    darling test statistic we'll use a set
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    of piecewise functions to calculate the
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    P value from that test statistic and
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    generally we use the P value and compare
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    it against a critical value to determine
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    whether or not um we can assume the the
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    data follow whatever distribution it
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    is
الوسوم
  • Anderson-Darling test
  • goodness of fit
  • hypothesis testing
  • distribution
  • z-score
  • test statistic
  • P-value
  • critical value
  • heavier tails
  • engineering