What would you do when you data contained an obvious "outlier"?

I am trying to find the range and average of:
25, 4, 5, 4, 5, 4, 5, 4, 5, 4 where 25 is the 'obvious outlier'.

Question

What would you do when you data contained an obvious "outlier"? 

I am trying to find the range and average of: 
25, 4, 5, 4, 5, 4, 5, 4, 5, 4 where 25 is the 'obvious outlier'.

trancenova · Answer

Hmm it all depends on the problem. Is this a problem from a textbook in which they expect you to deal with outliers in a certain way?

In some things you would find the average/range without the outlier. If you are making a box and whisker plot you usually plot the outlier as a dot outside of the range.

anonymous · Answer

I am only finding the range and average of 'statistic and data' in which I am comparing two datas, one of them contains and 'outlier' that I am not sure what to do with, and it is one of the questions.  I am unsure what it is, it is from a packet with information but does not explain anything about outliers.  I do know how to find range/averages, but a little forgetful on outliers.

trancenova · Answer

Hmmm.. The general "rule-of-thumb" with outliers is if they are above 1.5 times the inter-quartile range you exclude them from your calculations. Though I'm no too sure what they would want you to do (most probably exclude).

trancenova · Answer

Oh hang on, I think I've got my definitions wrong, wolfram mathworld says "A convenient definition of a outlier is a point which falls more than 1.5 times the interquartile range above the third quartile or below the first quartile." http://mathworld.wolfram.com/Outlier.html

anonymous · Answer

So you would drop it then, correct?  Completely drop it from the numbers...?

trancenova · Answer

Hmm I would yes, however I am a little unsure so take it with a grain of salt (hopefully someone else may be able to help).

I'm trying to remember if there is a difference in terms of outliers for the "statistic" and the "data".

anonymous · Answer

I see, if it helps any... I am working with the 'Scientific Method'..

trancenova · Answer

Dang, that probably means they're intending for you to know the difference. Does it mention anywhere if there is a difference between "statistic" and "data" in terms of means.

trancenova · Answer

Oh chucks! Just remembered I need to be somewhere - really sorry! will be back in an hour or so..

anonymous · Answer

Well it just shows data, when I said statistics, that is  what I meant it just the data numbers.

anonymous · Answer

Oh, okay, well thank you anyways.