You are viewing an obsolete version of the DU website which is no longer supported by the Administrators. Visit The New DU.
Democratic Underground Latest Greatest Lobby Journals Search Options Help Login

Reply #92: You are intuitively asking exactly the right question! [View All]

Printer-friendly format Printer-friendly format
Printer-friendly format Email this thread to a friend
Printer-friendly format Bookmark this thread
This topic is locked.
Home » Discuss » Topic Forums » Election Reform Donate to DU
Sancho Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Jun-17-07 06:34 AM
Response to Reply #89
92. You are intuitively asking exactly the right question!
For one example, two decades ago a well-known statistician described your question (including election polls as one example) in a popular published article that was reproduced in several journals and reports:

"Eelworms, Bullet Holes, and Geraldine Ferraro: Some Problems in Statistically Adjusting for Survey Nonresponse"
Wainer, Howard, 1987
There is no safety in numbers. When data are gathered from a sample in which the selection criteria are unknown, many problems can befall the unwary investigator. This paper explores some of these problems and discuss some solutions. The authors explore methods of covariance adjustment as well as more explicitly model-based adjustment methods. Among the latter, Heckman's Selection Model, Rubin's Mixture Model, and Tukey's Simplified Selection Model are discussed.

The conclusion of the article is simple. All the "weights" and "transformations" will not give a satisfactory result to account for "non-ignorable non-response". The only solution is to use "heroic methods" to get a proper sample.

In this case, the pollsters avoid getting the proper samples and continue to produce non-generalizable results for many questions. Reliance on parametric distributions and corrections (called weighting in the case of exit polls) to estimate error becomes a wild guess when the underlying distributions of the non-respondents are unknown.

Sorry if that seems too technical...
Printer Friendly | Permalink | Reply | Top

Home » Discuss » Topic Forums » Election Reform Donate to DU

Powered by DCForum+ Version 1.1 Copyright 1997-2002
Software has been extensively modified by the DU administrators

Important Notices: By participating on this discussion board, visitors agree to abide by the rules outlined on our Rules page. Messages posted on the Democratic Underground Discussion Forums are the opinions of the individuals who post them, and do not necessarily represent the opinions of Democratic Underground, LLC.

Home  |  Discussion Forums  |  Journals |  Store  |  Donate

About DU  |  Contact Us  |  Privacy Policy

Got a message for Democratic Underground? Click here to send us a message.

© 2001 - 2011 Democratic Underground, LLC