# Thread: question from the statistically challenged

1. example: I would like to take the median of 3 year's worth of data to compare to another three year's worth of data. The data vary seasonally.

Data set 1: The 1st year has 287 daily data points, the 2nd 77 daily data points, and the 3rd year 325 daily data points.
Data set 2: The 1st year has 347 daily data points, the 2nd 365 daily data points, and the 3rd year 366 daily data points. The data also vary seasonally.

I'm good at obvious: in layman's terms, the data will be unequally weighted in the first data set

(1) is this a situation where it is stupid to use median?
(2) assuming it's not, my thought is to look at the monthly medians and compare then. This may or may not help, depending on the distribution of the data throughout the year for the data sets with fewer data points.
(3) something else?

Suggestions appreciated.
Thanks.

2. I'd start by plotting the data in a scatter chart to see what patterns emerge.

3. Hi,

Whether or not you need the median function or an "ordinary" average depends on the nature of the data, I'm no expert there.
To detect whether or not te difference between two averages is statistically significant you need the so-called t-test.
I found a good description here:

http://www.stattutorials.com/EXCEL/EXCEL_TTEST2.html

and a tutorial here:

http://www.nursing.ucla.edu/researchoffice.../Stat_Excel.pdf

And finally, this resource has all the technical information you'd need:

t-test for independent samples (click the basic statistics button on the right)

4. [quote name='pieterse' post='800078' date='27-Oct-2009 11:16']Hi,

Whether or not you need the median function or an "ordinary" average depends on the nature of the data, I'm no expert there.
To detect whether or not te difference between two averages is statistically significant you need the so-called t-test.
I found a good description here:

http://www.stattutorials.com/EXCEL/EXCEL_TTEST2.html

and a tutorial here:

http://www.nursing.ucla.edu/researchoffice.../Stat_Excel.pdf

And finally, this resource has all the technical information you'd need:

t-test for independent samples (click the basic statistics button on the right)[/quote]

Thanks to both of you.

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