How do we calculate percent error without a theoretical value?

[rachelle]

% Deviation vs. % Error??

Hey guys, what's the difference between percent deviation and percent error?? I'm totally confused... how do I compare those two percentages? Any explanation or links that can help me with this so I can understand better is much appreciated! Thanks~

Rachelle

 

[jtbell]

Does this help?

http://www.shodor.org/UNChem/math/stats/

 

[rachelle]

Yes! Thank you :)

But can you tell me one more thing... what does the percent deviation tell me? As oppose to my percent error..? For instance I get my percent deviation to be 5%, and my percent error = 11%. What does this tell me?

Thanks in advance~

 

[FredGarvin]

The deviation is based on the mean of the sample as being your point of reference for the measurement. The error is based on a theoretic value expected. The deviation doesn't have to be a theoretical expected value. It just happens to be the mean.

Your results mean that the data you collected was skewed. The man of your data was not in line with the theoretical expected value.

 

[nmah]

Does this help?

http://www.shodor.org/UNChem/math/stats/

this example have theoretical value which is 54 celsius.but what if we don't have theoretical value?how can we calculate error?