# significance test

I've analysed newspapers by counting the language distributions of the articles.

The results look like that:

Day 1               Day 2              Day 3

Economy             Economy            Economy
language 1: 0,35    language 1: 0,30   language 1: 0,90
language 2: 0,11    language 2: 0,10   language 2: 0,00
language 3: 0,54    language 3: 0,60   language 3: 0,10

Sports              Sports             Sports
language 1: 0,40    language 1: 0,30   language 1: 1.00
language 2: 0,20    language 2: 0,20   language 2: 0,00
language 3: 0,40    language 3: 0,50   language 3: 0,00


I've have already posted another question on that topic (Remove statistical outliers), but here comes my second problem. First of all, I want to remove all statistical outliers from data (e.g. day 3), to make it "clean" (see my other question (other post). After that, I want to terminate which changes in my data are just "noise" and witch are significant changes. But I'm not sure how to do it.

I was thinking of the following approach:

I could calculate the standard deviation (like in my other post) and treat every value outside of it as a "significant change". But I think this will cause a mistake if all my values are slightly increasing or decreasing.

Is there any mathematical technique to find the significant changes in my data?