On 13 Apr 2004 06:32:25 -0700, [EMAIL PROTECTED] (Chris Toppe) wrote: > I have to explain my data before I can ask my question. I have survey > data on volunteering. The data were collected using an RDD > methodology. The data suffer from two problems -- non-response bias > (people opting out of the survey) and response bias (people giving the > socially accetpable answer). I can't tell the degree to which either > impacts my estimations, but I know they do. In addition to answering > questions about volunteering, the respondents were also asked if they > voted in the last presidential election (the data were collected in > the spring of 2001, not long after the election of 2000). Seventy > percent (70%) of the respondents said they voted, which is much higher > than the 51% who actually voted. I don't know if my higher voting > rate is a non-response bias or a response bias, just that it's too > high. I also know that 44% said they volunteered. With me so far? > > What I want to do is adjust the volunteering rate to correct for the > known bias. There is support in the literature for adusting a sample > to known population parameters, something that is done frequently when > a sample is adjusted to fit paramters such as gender, age, race, etc., > but I can find nothing that talks about using an embedded question > proportion to adjust another proportion. In other words, I want to > adjust the sample so that 51% are voters, thereby gaining a more > accurate estimation of the percentage who are volunteers. Still with > me?
I think you want to do some book-research. It seems to me that your 70%-claimed, 51% actual, may be about right, for the number who will *claim* to have voted in an much- discussed election. Does the group of 'voters' include most of the volunteers? Does this mean that the 44% will be inflated by a similar fraction? - I don't know. That's why I think you want to know what the careful literature says, and that should be important in your conclusions. > > I can do a simple ratio adjustment (51 is to 70 as X is to 44), but > that doesn't take into account the fact that some people are more > likely to be volunteers than are others. I've been struggling with > logistic regression as an approach to this, but without success. Does > anyone have any suggestions on how I can approach this? -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
