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PDF of Lecture Notes - School of Mathematical Sciences

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1. DISTRIBUTION THEORY<br />

3. Gamma (K, λ) distribution can be interpreted as the waiting time until the K th<br />

occurrence in a Poisson process.<br />

1.2.4 Beta density function<br />

Suppose Y 1 ∼ Gamma (α, λ), Y 2 ∼ Gamma (β, λ) independently, then,<br />

Remark:<br />

X = Y 1<br />

Y 1 + Y 2<br />

∼ B(α, β), 0 ≤ x ≤ 1.<br />

Figure 8: Beta Distribution<br />

1.2.5 Normal distribution<br />

X ∼ N(µ, σ 2 ); M X (t) = e tµ e t2 σ 2 /2 .<br />

1.2.6 Cauchy distribution<br />

Possible values: x ∈ R<br />

<strong>PDF</strong>: f(x) = 1 ( ) 1<br />

; (location parameter θ = 0)<br />

π 1 + x 2<br />

10

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