Update: Turns out I did my joins incorrectly. I first learned about reshaping survey data with the Tableau Pivot add-on to Excel through Steve Wexler's 2014 Tableau Conference presentation, then ultimately followed his updated instructions for reshaping within Tableau 10; however, I had the 2014 instructions in mind and unwittingly mixed the two methodologies, which resulted in a duplication of my demographic information, which is why the Count Negative field ended up multiplying everything by 4.
Solution: Only join 3 extracts (Value data, Label data, and Question Helper); a 4th Demographic extract is redundant and causes multiplicity issues.
I'm also trying to show survey data using Gantt bars, and have hit a snag that also happened when I tried to follow the previous postings on divergent Gantt charts.
I've reshaped the data, and created the "Cross Tab" so that I can see the calculation results:
I'm using the formula from the blog post to calculate Gantt Start, but as you can see above, instead of getting -26% for the first question, I get -0.26, which is somewhat correct, but downstream calculations are wrong - apparently they don't recognize it as 26%, but as a small fraction.
Sorry for the late reply. I think it may be a data format issue; if the default isn't set to percent, Tableau returns the number format. Right click your Gantt Start measure --> Default Properties --> Number format --> Percentage should do the trick!