src/chisquare.html

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    <title>Chi-square distribution</title>
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<h1>Chi-square distribution</h1>

<p class="description">
    A sum of the squares of $k$ independent <a href="./standardnormal.html">standard normal</a> random variables
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    <div class="slider-label">$k$</div>
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<div class="formula">
$$
    Z_1^2 + Z_2^2 + \cdots + Z_k^2 \;\sim\; \chi^2(k) 
$$
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<div class="formula">
$$
    f(x) = 
    \begin{cases}
        \frac{x^{\frac{k}{2}-1}e^{-\frac{x}{2}}}{2^{\frac{k}{2}}\Gamma\big(\frac{k}{2}\big)}, & \text{if $x > 0$,} \\
        0,                      & \text{otherwise.}
    \end{cases}
    \\[24pt]
    \text{where $k$ is the degree of freedom (the number of the squares)} \\
    \\
    \text{and $\Gamma\bigg(\frac{k}{2}\bigg)$ is the gamma function.}
$$
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