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伯努利分布(Bernoulli distribution,又名两点分布或者0-1分布,是一个离散型概率分布,为纪念瑞士科学家雅各布·伯努利而命名。)若伯努利试验成功,则伯努利随机变量取值为0。记其成功概率为 ${\displaystyle p(0{\leq }p{\leq }1)}$,失败概率为 ${\displaystyle q=1-p}$。
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对于伯努利分布来说:
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概率质量函数为:
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$$
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f_X(x) = p^{x}(1-p)^{1-x} = \left\{
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\begin{aligned}
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p if x = 1, \\\\
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q if x = 0.
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\end{aligned}
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\right.
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$$
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$$\displaystyle f_{X}(x)=p^{x}(1-p)^{1-x}= \left\{ {\begin{aligned}p&{\mbox{if }}x=1,\\ q\ &{\mbox{if }}x=0.\\ \end{aligned}}\right.$$
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期望为:
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$$\displaystyle \operatorname {E} [X]=\sum \_{i=0}^{1}x_{i}f_{X}(x)=0+p=p $$
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