Calculating Variance Between Two Different Data Sets

Hi there,

I've experienced a bit of an issue when trying to compare percentage variance between two different data sets. I'm not sure whether my minds gone completely blank or whether this is much more difficult than I anticipated.

I've attached an example of what I'm dealing with to this post, to help provide some context.

The tables I already have displayed show the number of sales by site relative to the that month. This is great as I can see who is performing the best in terms of sale volumes.

The challenge I am faced with now it calculating the variance for each location as the total number of sales are different in each table. The question I'm trying to answer (or someone is expecting me to answer) is "Since January 2011, what is the difference in sales by location, relative the the volumes in that month?".

It was suggested that I needed to normalize the data, however I'm not an analyst nor am I great at math! Any help or guidance would be greatly appreciated!

Thanks,
Lee

hello, see attached file
Example(1).zip

Thanks Berna11.

The example you have attached is showing the difference between the two percentages, however I need to establish the difference between the two volumes for each location, expressed as a percentage relative to the volumes in the month. Any ideas?

Hello, sorry but what should appear in cell K4?

Can you give examples?