I wish the table of underlying data was available so that a logistic regression could be run to see whether variables like campaign contributions do indeed predict support for SOPA after age and number of years served have been partialled out.

The data is pretty easily accessible as JSON - however, here's the data I used: http://pastebin.com/nRYv40U8

Firstly, a boxplot with the quotient of entertainment contributions to entertainment & internet contributions.

http://i.imgur.com/FWQWy.png

You can see quite easily that there's a difference which is also significant (95%, t = -4.73).

I've also done a logistic regression correcting with age, party (is_democrat), seniority and quota of contributions (quota_ent).

  ------------------------------------------------------------------------------
       support |      Coef.   Std. Err.      z    P>|z|     [95% Conf. Interval]  
  -------------+----------------------------------------------------------------
           age |   .0258551   .0358136     0.72   0.470    -.0443382    .0960485
   is_democrat |  -1.252883   .6243361    -2.01   0.045    -2.476559   -.0292067
     seniority |  -.0262688   .0381962    -0.69   0.492     -.101132    .0485943
     quota_ent |   5.839435   1.447732     4.03   0.000     3.001933    8.676938
         _cons |  -1.968467    2.01512    -0.98   0.329    -5.918029    1.981096
  ------------------------------------------------------------------------------

The AUC is 0.8089 which is quite okay. Furthermore, it would be interesting to test whether location is a significant factor.

Edit: @adamtaylor: Here's a scatter plot with each contribution, transformed with log(1 + x) for readability: http://i.imgur.com/MRciL.png

Hmm, that scatterplot suggests a less straightforward relationship; the for/against dots look like they plausibly came from slightly different distributions, but not very much different ones.

Isn't that what the "$ Difference" sort shows? Or did they just add that?

Just added

EDIT: This shows as a ratio (+$ from internet : no difference : +$ from movie).

For - 23 : 3 : 55 0.28 : 0.04 : 0.67

Against - 15 : 0 : 6 0.71 : 0 : 0.28

So ~70% of people who received more funding from one party support the bill accordingly.