Jump to content
Sign in to follow this  
hamzah

What method is this?

Recommended Posts

Lets say I have three values - 917, 914 and 913. Take an average I get 915 (approx).

 

Now see how far each value is from the average...

 

917 - 915 = 2

915 - 914 = 1

915 - 913 = 2

 

(2+1+2)/3 = 2 (approx)

 

so the value is (915 +/- 2)

 

what is this method called?

Share this post


Link to post
Share on other sites

LOL

 

It does ring a bell of some statistical method with 'some result' but I can't remember.

Share this post


Link to post
Share on other sites
Neurocomp2003 said in post # :

....method?

this isn't a method its error measurement.

 

yeah thats what I'm doing, error measurements...but the way I calculated it...does that technique have a name or anything?

Share this post


Link to post
Share on other sites

Thats almost like variance, which takes the sum of all the squares of the differences between the means and values and then divides by the number of samples.

 

In your case, the variance would be:

 

[math]http://blike.com/mimetex/mimetex.cgi?4$var=\frac{(1-2)^2+(2-2)^2+(3-2)^2}{3}[/math]

 

grr..my cgibin sucks

Share this post


Link to post
Share on other sites

Hamza is talking about the mean deviation.

 

The measure of how much any given observation varies from the mean is a deviation. These will have either positive or negative values. The mean of them will always be zero (as the mean is the arithmetical centre of the data). So, to calculate the mean deviation, we ignore the sign (+ or -) which gives us for each deviation the absolute deviation, shown as |d|.

 

So, the two ways of calculating the mean deviation is either:

 

Sum of |x - mean|

----------------------

             N

 

 

or

 

Sum of |d|

-------------

      N

 

 

The Standard deviation is: 

 

                                       (Sum of (X - mean)^2) 

The square root of:     -----------------------------

                                                       N

 

 

(or N-1 for the sample SD).

 

Dang! I wish I knew how to use the formula doohickey.

Share this post


Link to post
Share on other sites

You're working out the mean absolute deviation from the mean, but you really ought to use a more accurate value for the mean of the numbers.

Share this post


Link to post
Share on other sites

Well I've completed an experiment to determine the specific heat capacity of Aluminium...and the book quotes "910J/kg.k"...so I thought I'd stick to the same format as them.

Share this post


Link to post
Share on other sites

Fluent i do not think standard error and effective reduction is applicable at this level.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.