Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

[SOLVED] What is the difference between mean and expected value.

Status
Not open for further replies.
A

anand_jha_30

Member level 2
Member level 2
Joined
Oct 29, 2010
Messages
50
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
1,616
What is the difference between mean and expected value. If they are anyhow different is there any example where the value of the two are different.
 

Suppose the data set is {1,2,2,3,3,3,4,4,5}. Here the mean is 3. One will calculate EV by (1/9)*1+(2/9)*2+(3/9)*3+(2/9)*4+(1/9)*5. Here again answer is 3. Actually when we multiply by weight we get our data back and we essentially do the same thing. So I again ask is there any difference between the two. can you give an example in your support.
 

Assume you have the following: two, 1's; ten, 2's; and one, 100. The mean is 61 (edit: 9.4), but the most likely number is 2.

There are all sorts of distributions besides the "normal" distribution. Two common ones seen in biological sciences are the geometric (e.g., 1,2,4,8,16...)(See:Geometric mean - Wikipedia, the free encyclopedia) and log-normal (Log-normal distribution - Wikipedia, the free encyclopedia).

The "median" is useful a parameter for evaluating distributions where the arithmetic average is not the most likely.

John
 
Last edited:

@jpanhalt . These things I know. I am asking about. What is the difference between mean and expected value. If there is any? Also in your example mean is 9.3
 
Last edited:

If you do an experiment, the expected value is given by the average of all the possible values weighted by their probability. The mean instead is the actual mean value you have after N runs. Statistically:

Average --> Expected Value for N --> infinite.

Of course if you calculate the expected value and the mean on a finite set of value the two calculation will give the same result.
 
Statistically, in probability theory, statistical average means expected value.

Expected value for "first moment" is the "mean" and it is still possible to have expected value for "second moment", "third moment", up to the "Nth moment".

Therefore,

Expected value for first moment = mean

Expected value for second moment is not equal to mean

Expected value for third moment is not equal to mean

Expected value for Nth moment is not equal to mean
 
Last edited:
Dear Guys,

Please, don't generate confusion for a simple question!
Several of the above answers are completely wrong. Some other go out of the subject.
In probability theory (it is obvious that the question is telling about it), mean and expected value are the same thing.
Please, check your answers before give them.
Regards

Z
 

Please, have a look to:
**broken link removed**
go to chapter 18 - The expected value.
We are speaking about a sequence generated by multiple independent experiments, so the mean is not the same thing of the expected value.
 
  • Like
Reactions: Phummy

    P

    Phummy

    Points: 2
    Helpful Answer Positive Rating
albbg said:
We are speaking about a sequence generated by multiple independent experiments, so the mean is not the same thing of the expected value.
Click to expand...

If you calculate the average of a sequence generated by multiple independent experiments, that is called sample mean.
The "expectad value", "statistical average" or simply "mean" of a random variable is related to its distribution, not to an experiment.
Given a composite experiment, the above-mentionned sample mean is itself a random variable. Instead, the mean is a number.
Regards

Z
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top