It certainly has been an educational week for those of us interesting in polling.

First came the illuminating disclosure that liberal polling company Public Policy Polling sometimes does not release the results of polls with unexpected results.

Then came this interesting article by TNR’s Nate Cohn, showing that PPP’s polling methodology includes a variety of questionable practices such as “random deletion” of respondents.

Then came Nate Silver’s statement that he will continue relying on PPP data even though he thinks PPP’s polls are crap.

Drew Linzer, a Ph.D. political scientist who knows his stuff, likened random deletion to “intuitive ‘shrinkage’ weighting.”

We’re no experts, but it sounds like he’s saying this is a method used to get the sample to mirror the population at large.

If that sounds like smoke and mirrors, don’t worry, because all pollsters do it:

Well, that’s certainly reassuring.


Nate Silver: PPP’s polls suck but I’ll keep using them

Nate Silver blasts Public Policy Polling for suppressing pro-recall poll result; Update: PPP apologizes for defending itself in public(!)