Recent content by Ad VanderVen

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    I The covariance of a sum of two random variables X and Y

    The answer indeed follows from Wikipedia: article Covariance, section Covariance of linear combinations (sixth equation). Reference: https://www.physicsforums.com/threads/the-covariance-a-sum-of-two-random-variables-x-and-y.1056159/
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    I The covariance of a sum of two random variables X and Y

    The summary: Suppose you have three random variables X, Y and K. Suppose X and Y are independent, but each correlated with K. Suppose Z = X+Y. Is it true that in probability theory the covariance of Z with K is equal to the sum of the covariance of X with K and the covariance of Y with K? is...
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    I The covariance of a sum of two random variables X and Y

    Suppose X and Y are random variables. Is it true that Cov (Z,K) = Cov(X,K)+Cov(Y,K) where Z=X+Y?
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    I The third central moment of a sum of two independent random variables

    Is it true that when X and Y are independent, E ({X+Y}3) = E (X3)+E(Y3)?
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    A Standard error of the coefficient of variation

    On https://influentialpoints.com/Training/standard_error_of_coefficient_of_variation.htm I read: $$SE(CV) \, = \, \frac{CV}{\sqrt{2 \, n}} \, \sqrt{1+2 \, \left(\frac{CV}{100}\right) ^2}$$ where ##SE## is the standard error, ##CV## is the coefficient of variation and ##n## is the number of...
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    A Standard error of the coefficient of variation

    What is the standard error of the coefficient of variation in an exponential distribution?
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    A The standardized and unstandardized canonical correlation coefficients

    You simply define the standardized and unstandardized correlation coefficient, but we are talking about the canonical correlation coefficient here.
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    A The standardized and unstandardized canonical correlation coefficients

    The output of SPSS 27 Canonical Correlation gives the standardized and unstandardized canonical correlation coefficients. What exactly are the standardized and unstandardized canonical correlation coefficients and what is the difference between them?
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    History Were Rahu and Ketu considered true planets in ancient times?

    Sure, I had read that article a long time ago, but it didn't help answer my question at all.
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    History Were Rahu and Ketu considered true planets in ancient times?

    Indeed it is not physics, but it is very important for the history of physics. For example, what Galileo Galilei wrote aboot astronomy is imporatfor the jhsistpry of astronomt Please, can you give me the web address of the history section? I couldn't find it on PhysicsForums.
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    History Were Rahu and Ketu considered true planets in ancient times?

    It is indeed not physics, but it is very important to the history of physics. For example, what Galileo Galilei wrote about astronomy is important for the knowledge of the history of astronomy. Unfortunately, there is no section on the history of astronomy on PhysicsForums. That's why I have to...
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    History Were Rahu and Ketu considered true planets in ancient times?

    This is a physics question! I ask if there is any written evidence for the idea that scholars in ancient India thought that Rahu and Ketu were real planets or at least celestial bodies. I need this information in connection with an article I am writing about a certain period in the history of...
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    History Were Rahu and Ketu considered true planets in ancient times?

    TL;DR Summary: Were Rahu and Ketu considered true planets in ancient times before 500 AD and is there any evidence for this in the ancient scriptures? Nowadays when people ask what Rahu and Ketu are, it is always said that those names refer to the lunar nodes. Now I thought that that...
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    B Speed of Point on Expanding Sphere

    I mean ##r(t) \, = \, b \, t## where ##t## represents time and ##0 \, < \, b##..
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    B Speed of Point on Expanding Sphere

    I mean it purely mathematically.