check if estimation is unbiased?
$begingroup$
Assume we that we calculate the expected value of some measurements $x=dfrac {x_1 + x_2 + x_3 + x_4} 4$. what if we dont include $x_3$ and $x_4$, but instead we use $x_2$ as $x_3$ and $x_4$. Then We get the following expression $v=dfrac {x_1 + x_2 + x_2 + x_2} 4$.
How do I know if $v$ is a unbiased estimation of $x$?
I am not sure how to approach this problem, any ideas are appreciated!
statistics estimation-theory parameter-estimation
$endgroup$
add a comment |
$begingroup$
Assume we that we calculate the expected value of some measurements $x=dfrac {x_1 + x_2 + x_3 + x_4} 4$. what if we dont include $x_3$ and $x_4$, but instead we use $x_2$ as $x_3$ and $x_4$. Then We get the following expression $v=dfrac {x_1 + x_2 + x_2 + x_2} 4$.
How do I know if $v$ is a unbiased estimation of $x$?
I am not sure how to approach this problem, any ideas are appreciated!
statistics estimation-theory parameter-estimation
$endgroup$
1
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12
add a comment |
$begingroup$
Assume we that we calculate the expected value of some measurements $x=dfrac {x_1 + x_2 + x_3 + x_4} 4$. what if we dont include $x_3$ and $x_4$, but instead we use $x_2$ as $x_3$ and $x_4$. Then We get the following expression $v=dfrac {x_1 + x_2 + x_2 + x_2} 4$.
How do I know if $v$ is a unbiased estimation of $x$?
I am not sure how to approach this problem, any ideas are appreciated!
statistics estimation-theory parameter-estimation
$endgroup$
Assume we that we calculate the expected value of some measurements $x=dfrac {x_1 + x_2 + x_3 + x_4} 4$. what if we dont include $x_3$ and $x_4$, but instead we use $x_2$ as $x_3$ and $x_4$. Then We get the following expression $v=dfrac {x_1 + x_2 + x_2 + x_2} 4$.
How do I know if $v$ is a unbiased estimation of $x$?
I am not sure how to approach this problem, any ideas are appreciated!
statistics estimation-theory parameter-estimation
statistics estimation-theory parameter-estimation
edited Dec 7 '15 at 11:55
dumble24
asked Dec 6 '15 at 19:55
dumble24dumble24
1016
1016
1
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12
add a comment |
1
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12
1
1
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
[EDIT: Assumed $x_k$ are random variables.]
We say $v$ is an estimator of random variable $x$ if $E[v]=E[x]$, where $E[cdot]$ is expectation of random variables.
Recall that expectation is a linear operator, i.e. if $X$ and $Y$ are random variables and $a,b$ are constants, $E[aX+bY]=aE[X]+bE[Y]$. So we get $E[x]=frac{1}{4}(E[x_1]+E[x_2]+E[x_3]+E[x_4])$, and $E[v]=frac{1}{4}(E[x_1]+3E[x_2])$. Notice that $E[x]=E[v]$ is equivalent to $E[x]-E[v]=0$.
So $v$ is an unbiased estimator if $E[x]-E[v]=0 Leftrightarrow E[x_3]+E[x_4]-2E[x_2]=0.$
$endgroup$
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
add a comment |
$begingroup$
Let $theta$ be some parameter. Let $X$ be an estimator.
$X$ is called an unbiased estimator for $theta$ if $E[X] = theta$.
Note that $X$ is a random variable (or random vector) while $theta$ would be a scalar (or vector).
Example
Let's say $x_1$ and $x_2$ are random variables with $E[x_1] = E[x_2] = mu$. Then estimator $y = frac{1}{5} x_1 + frac{4}{5} x_2$ would be an unbiased estimate of $mu$ since $E[y] = mu$.
$endgroup$
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f1563004%2fcheck-if-estimation-is-unbiased%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
[EDIT: Assumed $x_k$ are random variables.]
We say $v$ is an estimator of random variable $x$ if $E[v]=E[x]$, where $E[cdot]$ is expectation of random variables.
Recall that expectation is a linear operator, i.e. if $X$ and $Y$ are random variables and $a,b$ are constants, $E[aX+bY]=aE[X]+bE[Y]$. So we get $E[x]=frac{1}{4}(E[x_1]+E[x_2]+E[x_3]+E[x_4])$, and $E[v]=frac{1}{4}(E[x_1]+3E[x_2])$. Notice that $E[x]=E[v]$ is equivalent to $E[x]-E[v]=0$.
So $v$ is an unbiased estimator if $E[x]-E[v]=0 Leftrightarrow E[x_3]+E[x_4]-2E[x_2]=0.$
$endgroup$
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
add a comment |
$begingroup$
[EDIT: Assumed $x_k$ are random variables.]
We say $v$ is an estimator of random variable $x$ if $E[v]=E[x]$, where $E[cdot]$ is expectation of random variables.
Recall that expectation is a linear operator, i.e. if $X$ and $Y$ are random variables and $a,b$ are constants, $E[aX+bY]=aE[X]+bE[Y]$. So we get $E[x]=frac{1}{4}(E[x_1]+E[x_2]+E[x_3]+E[x_4])$, and $E[v]=frac{1}{4}(E[x_1]+3E[x_2])$. Notice that $E[x]=E[v]$ is equivalent to $E[x]-E[v]=0$.
So $v$ is an unbiased estimator if $E[x]-E[v]=0 Leftrightarrow E[x_3]+E[x_4]-2E[x_2]=0.$
$endgroup$
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
add a comment |
$begingroup$
[EDIT: Assumed $x_k$ are random variables.]
We say $v$ is an estimator of random variable $x$ if $E[v]=E[x]$, where $E[cdot]$ is expectation of random variables.
Recall that expectation is a linear operator, i.e. if $X$ and $Y$ are random variables and $a,b$ are constants, $E[aX+bY]=aE[X]+bE[Y]$. So we get $E[x]=frac{1}{4}(E[x_1]+E[x_2]+E[x_3]+E[x_4])$, and $E[v]=frac{1}{4}(E[x_1]+3E[x_2])$. Notice that $E[x]=E[v]$ is equivalent to $E[x]-E[v]=0$.
So $v$ is an unbiased estimator if $E[x]-E[v]=0 Leftrightarrow E[x_3]+E[x_4]-2E[x_2]=0.$
$endgroup$
[EDIT: Assumed $x_k$ are random variables.]
We say $v$ is an estimator of random variable $x$ if $E[v]=E[x]$, where $E[cdot]$ is expectation of random variables.
Recall that expectation is a linear operator, i.e. if $X$ and $Y$ are random variables and $a,b$ are constants, $E[aX+bY]=aE[X]+bE[Y]$. So we get $E[x]=frac{1}{4}(E[x_1]+E[x_2]+E[x_3]+E[x_4])$, and $E[v]=frac{1}{4}(E[x_1]+3E[x_2])$. Notice that $E[x]=E[v]$ is equivalent to $E[x]-E[v]=0$.
So $v$ is an unbiased estimator if $E[x]-E[v]=0 Leftrightarrow E[x_3]+E[x_4]-2E[x_2]=0.$
edited Dec 6 '15 at 20:36
answered Dec 6 '15 at 20:02
manofbearmanofbear
1,579515
1,579515
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
add a comment |
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
How do we decide if $v$ is unbiased or not unbiased using $ E[x_3]+E[x_4]-2E[x_2]=0.$ as $x_2,x_3$ and $x_4$ are not defined?
$endgroup$
– dumble24
Dec 6 '15 at 21:01
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
What is this, if E[v] = E[x]?! Why are you taking expectations on the right hand side?
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:14
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Almost certainly dumble24 is in a classical statistics environment and is estimating some parameter, not another random variable.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 10:24
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
$begingroup$
Edited the question, added some more context.
$endgroup$
– dumble24
Dec 7 '15 at 11:58
add a comment |
$begingroup$
Let $theta$ be some parameter. Let $X$ be an estimator.
$X$ is called an unbiased estimator for $theta$ if $E[X] = theta$.
Note that $X$ is a random variable (or random vector) while $theta$ would be a scalar (or vector).
Example
Let's say $x_1$ and $x_2$ are random variables with $E[x_1] = E[x_2] = mu$. Then estimator $y = frac{1}{5} x_1 + frac{4}{5} x_2$ would be an unbiased estimate of $mu$ since $E[y] = mu$.
$endgroup$
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
add a comment |
$begingroup$
Let $theta$ be some parameter. Let $X$ be an estimator.
$X$ is called an unbiased estimator for $theta$ if $E[X] = theta$.
Note that $X$ is a random variable (or random vector) while $theta$ would be a scalar (or vector).
Example
Let's say $x_1$ and $x_2$ are random variables with $E[x_1] = E[x_2] = mu$. Then estimator $y = frac{1}{5} x_1 + frac{4}{5} x_2$ would be an unbiased estimate of $mu$ since $E[y] = mu$.
$endgroup$
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
add a comment |
$begingroup$
Let $theta$ be some parameter. Let $X$ be an estimator.
$X$ is called an unbiased estimator for $theta$ if $E[X] = theta$.
Note that $X$ is a random variable (or random vector) while $theta$ would be a scalar (or vector).
Example
Let's say $x_1$ and $x_2$ are random variables with $E[x_1] = E[x_2] = mu$. Then estimator $y = frac{1}{5} x_1 + frac{4}{5} x_2$ would be an unbiased estimate of $mu$ since $E[y] = mu$.
$endgroup$
Let $theta$ be some parameter. Let $X$ be an estimator.
$X$ is called an unbiased estimator for $theta$ if $E[X] = theta$.
Note that $X$ is a random variable (or random vector) while $theta$ would be a scalar (or vector).
Example
Let's say $x_1$ and $x_2$ are random variables with $E[x_1] = E[x_2] = mu$. Then estimator $y = frac{1}{5} x_1 + frac{4}{5} x_2$ would be an unbiased estimate of $mu$ since $E[y] = mu$.
edited Dec 7 '15 at 10:17
answered Dec 7 '15 at 9:57
Matthew GunnMatthew Gunn
37618
37618
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
add a comment |
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
$begingroup$
Whoever modded this down was either sloppy or doesn't know what he/she is talking about.
$endgroup$
– Matthew Gunn
Dec 8 '15 at 3:59
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f1563004%2fcheck-if-estimation-is-unbiased%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
1
$begingroup$
So $v$ is the same thing as $x$? If that's not what you meant, then you need to clarify your question.
$endgroup$
– Michael Hardy
Dec 6 '15 at 20:07
$begingroup$
I assumed here that $x_k$ are random variables.
$endgroup$
– manofbear
Dec 6 '15 at 20:35
$begingroup$
x is expected value of a random variable
$endgroup$
– dumble24
Dec 6 '15 at 21:05
$begingroup$
(x1+x2+x3+x4)/4 calculates the expected value if a random variable has exactly four, equiprobable possible outcomes x1, x2, ..., x4. Alternatively, if x_1, x_2, ... x_4 denote 4 independent draws form some probability distribution, then (x1+x2+x3+x4)/4 is an estimator of the expected value, but it is not the actual expected value! To be precise, this is an important distinction.
$endgroup$
– Matthew Gunn
Dec 7 '15 at 23:12