$X_{1},…,X_{n}$ ~ $Ber(p)$ what can I say about $exp(lambda X_{1}),…,exp(lambda X_{n})$
$begingroup$
Let $X_{1},...,X_{n}$ ~ $Ber(p)$ be independent, and $lambda > 0$. What can I say about $exp(lambda X_{1}),...,exp(lambda X_{n})$ with respect to $mathbb E[exp(lambda X_{i})]$?
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
I assume $exp(lambda X_{i})$ will be bernoulli distributed but I fail to find a way to determine the Bernoulli coefficients, and how to prove these. Any ideas?
probability-theory probability-distributions random-variables independence
$endgroup$
add a comment |
$begingroup$
Let $X_{1},...,X_{n}$ ~ $Ber(p)$ be independent, and $lambda > 0$. What can I say about $exp(lambda X_{1}),...,exp(lambda X_{n})$ with respect to $mathbb E[exp(lambda X_{i})]$?
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
I assume $exp(lambda X_{i})$ will be bernoulli distributed but I fail to find a way to determine the Bernoulli coefficients, and how to prove these. Any ideas?
probability-theory probability-distributions random-variables independence
$endgroup$
add a comment |
$begingroup$
Let $X_{1},...,X_{n}$ ~ $Ber(p)$ be independent, and $lambda > 0$. What can I say about $exp(lambda X_{1}),...,exp(lambda X_{n})$ with respect to $mathbb E[exp(lambda X_{i})]$?
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
I assume $exp(lambda X_{i})$ will be bernoulli distributed but I fail to find a way to determine the Bernoulli coefficients, and how to prove these. Any ideas?
probability-theory probability-distributions random-variables independence
$endgroup$
Let $X_{1},...,X_{n}$ ~ $Ber(p)$ be independent, and $lambda > 0$. What can I say about $exp(lambda X_{1}),...,exp(lambda X_{n})$ with respect to $mathbb E[exp(lambda X_{i})]$?
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
I assume $exp(lambda X_{i})$ will be bernoulli distributed but I fail to find a way to determine the Bernoulli coefficients, and how to prove these. Any ideas?
probability-theory probability-distributions random-variables independence
probability-theory probability-distributions random-variables independence
edited Jan 10 at 13:12
Ahmad Bazzi
8,0362724
8,0362724
asked Jan 10 at 12:32
SABOYSABOY
588311
588311
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
This is not true. Since $X_k$ are all discrete, then so is $exp(lambda X_k)$. Using the rule of discrete expectation, we can say that
$$E(exp(lambda X)) = sum_{x in lbrace 0,1 rbrace } Pr(X=x) exp(lambda x) = Pr(X=0)exp(lambda (0)) + Pr(X=1)exp(lambda (1))$$
Since $Pr(X=0) = 1-p$ and $Pr(X=1) = p$, we get
$$E(exp(lambda X)) = 1-p+ pexp(lambda )$$
$endgroup$
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
add a comment |
$begingroup$
Guide:
If $X_i=0$, we have $exp(lambda X_i)=1$, this happens with probability $1-p$.
What happens to $exp(lambda X_i)$ if $X_i=1$? what is the corresponding probability.
Now use the definition of expectation to compute the desired quantity.
$endgroup$
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
add a comment |
Your Answer
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
This is not true. Since $X_k$ are all discrete, then so is $exp(lambda X_k)$. Using the rule of discrete expectation, we can say that
$$E(exp(lambda X)) = sum_{x in lbrace 0,1 rbrace } Pr(X=x) exp(lambda x) = Pr(X=0)exp(lambda (0)) + Pr(X=1)exp(lambda (1))$$
Since $Pr(X=0) = 1-p$ and $Pr(X=1) = p$, we get
$$E(exp(lambda X)) = 1-p+ pexp(lambda )$$
$endgroup$
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
add a comment |
$begingroup$
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
This is not true. Since $X_k$ are all discrete, then so is $exp(lambda X_k)$. Using the rule of discrete expectation, we can say that
$$E(exp(lambda X)) = sum_{x in lbrace 0,1 rbrace } Pr(X=x) exp(lambda x) = Pr(X=0)exp(lambda (0)) + Pr(X=1)exp(lambda (1))$$
Since $Pr(X=0) = 1-p$ and $Pr(X=1) = p$, we get
$$E(exp(lambda X)) = 1-p+ pexp(lambda )$$
$endgroup$
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
add a comment |
$begingroup$
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
This is not true. Since $X_k$ are all discrete, then so is $exp(lambda X_k)$. Using the rule of discrete expectation, we can say that
$$E(exp(lambda X)) = sum_{x in lbrace 0,1 rbrace } Pr(X=x) exp(lambda x) = Pr(X=0)exp(lambda (0)) + Pr(X=1)exp(lambda (1))$$
Since $Pr(X=0) = 1-p$ and $Pr(X=1) = p$, we get
$$E(exp(lambda X)) = 1-p+ pexp(lambda )$$
$endgroup$
Well because $f_{lambda }(x):=e^{lambda x}$ is a continuous random variable, $(f_{lambda }(X_{i}))_{i=1,...,n}$ are independent and identically distributed.
This is not true. Since $X_k$ are all discrete, then so is $exp(lambda X_k)$. Using the rule of discrete expectation, we can say that
$$E(exp(lambda X)) = sum_{x in lbrace 0,1 rbrace } Pr(X=x) exp(lambda x) = Pr(X=0)exp(lambda (0)) + Pr(X=1)exp(lambda (1))$$
Since $Pr(X=0) = 1-p$ and $Pr(X=1) = p$, we get
$$E(exp(lambda X)) = 1-p+ pexp(lambda )$$
answered Jan 10 at 13:19
Ahmad BazziAhmad Bazzi
8,0362724
8,0362724
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
add a comment |
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
Why is $(f_{lambda}(X_{i}))_{i=1,...n}$ not i.i.d.?
$endgroup$
– SABOY
Jan 10 at 19:54
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
@SABOY i did not say it is not i.i.d .. i said it is not true meaning that it is not a continuous random variable. It is a discrete random variable.
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:56
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
Apologies, misunderstanding
$endgroup$
– SABOY
Jan 10 at 19:57
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
$begingroup$
no worries :) @SABOY
$endgroup$
– Ahmad Bazzi
Jan 10 at 19:59
add a comment |
$begingroup$
Guide:
If $X_i=0$, we have $exp(lambda X_i)=1$, this happens with probability $1-p$.
What happens to $exp(lambda X_i)$ if $X_i=1$? what is the corresponding probability.
Now use the definition of expectation to compute the desired quantity.
$endgroup$
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
add a comment |
$begingroup$
Guide:
If $X_i=0$, we have $exp(lambda X_i)=1$, this happens with probability $1-p$.
What happens to $exp(lambda X_i)$ if $X_i=1$? what is the corresponding probability.
Now use the definition of expectation to compute the desired quantity.
$endgroup$
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
add a comment |
$begingroup$
Guide:
If $X_i=0$, we have $exp(lambda X_i)=1$, this happens with probability $1-p$.
What happens to $exp(lambda X_i)$ if $X_i=1$? what is the corresponding probability.
Now use the definition of expectation to compute the desired quantity.
$endgroup$
Guide:
If $X_i=0$, we have $exp(lambda X_i)=1$, this happens with probability $1-p$.
What happens to $exp(lambda X_i)$ if $X_i=1$? what is the corresponding probability.
Now use the definition of expectation to compute the desired quantity.
answered Jan 10 at 12:35
Siong Thye GohSiong Thye Goh
100k1466117
100k1466117
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
add a comment |
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
If $X_{i}=1$ then $exp(lambda X_{i})=exp(lambda)$ The corresponding probability would be $0$ would it not, unless $lambda = 0$?
$endgroup$
– SABOY
Jan 10 at 12:46
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
the correponding probability should be $p$.
$endgroup$
– Siong Thye Goh
Jan 10 at 12:49
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
So we've got $P(exp(lambda X_{i})=exp(lambda))=p$ while $P(exp(lambda X_{i})=1)=1-p$, so a kind of Bernoulli distribution between two values $exp(lambda)$ and $1$?
$endgroup$
– SABOY
Jan 10 at 13:01
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
$begingroup$
It is a discrete distribution that only takes two values.
$endgroup$
– Siong Thye Goh
Jan 10 at 13:06
add a comment |
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