- #1
Melawrghk
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Homework Statement
I am trying to see if two sets of data represent the same values or not. I have:
Mean1 = 9.3155, stdev1 = 0.1334; mean2 = 9.3040, stdev2 = 0.1248;
N1 = N2 = 1000;
I got these values from my data using MATLAB (std() and mean());
Homework Equations
[itex]z = \frac{(mean1-mean2)}{\sqrt{stdev1^{2}/N1^{2}+stdev2^{2}/N2^{2}}}[/itex]
The Attempt at a Solution
Null hypothesis: Sets are different.
Alternative: Sets are the same.
Using the formula above I get z score of 63, which accepts my Null hypothesis that the two series are different.
However, I don't really seem to understand why they would be considered different given the fairly large standard deviation and close means. The way I think is kind of like - the second mean fits within mean1+/-stdev1, so shouldn't the z score be smaller?
Statistics isn't my strong suit, and this is for an electronics thing, but I'm curious what I'm thinking wrong exactly.