I'm looking for an application or workflow which integrates data values into the writing process Currently, on all of my projects, I do my data analysis, create my figures, put them into a word document, and then I start writing. I say things like "We saw a 35% reduction in the effectiveness of..."

100% of the time, these numbers change. We reach the discussion section and a co-author requests we change the analysis this or that way, or finds an error in my thinking.

Then, I need to go back and re-do the analysis. Then, I'll need to find every point of data that was potentially affected and manually change it in a word document. Occasionally, this back-and-forth leads to the introduction of errors.

I would love a writing platform that would allow me to integrate my data into the writing process. Instead of writing 

"We saw a 35% reduction in ..." 

I would say:

"We saw a &lt;% print(reduction.round()) %>% reduction in.."

Of course I could do this from scratch on my own computer, but I then lose the ability to collaborate. 

I'm wondering if anyone has had this problem, and how they have solved it?
One possible workflow is using R for producing the results, LaTeX for writing the report, and Sweave to integrate both. With either TexStudio or LyX (or any text editor that supports track changes) as writing environments and Dropbox, you can set up some sort of "collaboration".