- #1
kobe87
- 4
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Suppose that X is a random variable distributed in the interval [a;b] with pdf f(x) and cdf F(x). Clearly, F(b)=1. I only observe X for values that are bigger than y.
I know that [itex]E(X|X>y)=\frac{\int_y^b xf(x)dx}{1-F(y)}[/itex].
Moreover, [itex]\frac{∂E(X|X>y)}{∂y}=\frac{f(y)}{1-F(y)}[E(X|X>y)-y][/itex]
I would like to evaluate this derivative as y→b.I was trying with Hopital but I could not go anywhere. Looking at Wikipedia(http://en.wikipedia.org/wiki/Truncated_distribution#Expectation_of_truncated_random_variable) it appears that the solution to my question is 1/2 but I might be completely wrong.
I am new to this forum I hope that I opened this thread in the right section. Thanks to anyone who is willing to help me.
I know that [itex]E(X|X>y)=\frac{\int_y^b xf(x)dx}{1-F(y)}[/itex].
Moreover, [itex]\frac{∂E(X|X>y)}{∂y}=\frac{f(y)}{1-F(y)}[E(X|X>y)-y][/itex]
I would like to evaluate this derivative as y→b.I was trying with Hopital but I could not go anywhere. Looking at Wikipedia(http://en.wikipedia.org/wiki/Truncated_distribution#Expectation_of_truncated_random_variable) it appears that the solution to my question is 1/2 but I might be completely wrong.
I am new to this forum I hope that I opened this thread in the right section. Thanks to anyone who is willing to help me.