Standard Deviation: Can I remove some data?

Question

Hi all

Suppose That I have measured property "X" in 16 points of a rigid body. This rigid body is consisted of two different materials. In one of them, property X is around 1, and in the other X is around 5. When I measured X, I found a transition zone of X between material 1 and 2. My matrix is something like this:

X=[1.1 1.08 1.05 0.98 1.02 1.29 1.78 2.34 3.78 4.21 4.78 4.98 5.02 5.09 5.1 5.06]

As you can see my findings are reasonable and I expect low value for standard deviation in materials 1 and 2.
Now, I want to calculate standard deviation of data in material 1 and standard deviation of data in material 2. What should I do with the data of transition region (I mean [1.29 1.78 2.34 3.78 4.21])? If I suppose they are for material 1, the standard deviation in material 1 goes very high; Similarly, if I attribute them to material 2, the standard deviation in material 2 increases. Is there any rule to just neglect the transition data? If yes, could you please provide a reference for that (like a book or article) so that I can include it in my report? Because I can not write down I just neglected them.

Thank you very much

sasankamali · Answer

Then focus less on the statistical parameters and more on what might cause the variations in your data...people get hung up on the numbers too often and sometimes fails to see other interesting avenues of investigation when things don't seem to go as expected....good luck

Yes. Thanks for advice 🙂

DanPatterson_Retired · Answer

Then focus less on the statistical parameters and more on what might cause the variations in your data...people get hung up on the numbers too often and sometimes fails to see other interesting avenues of investigation when things don't seem to go as expected....good luck

sasankamali · Answer

Thank you Dan

But I think the data is OK cause I have done several tests and they are all almost similar.