There ya go...
ping
1. Rats lie!
2. If the polls show R up by more than 3 a lot of dems won’t bother to vote.
That’s a fabulous - and frankly pretty stunning - observation.
I’ll also point out that it’s the broadcast media tending to use the smaller sample sizes, which is a function both of their use of polls as a “news story” rather than for “science” (term used loosely), and of their desire to continually make their viewers feel that they have the freshest information available.
Rasmussen, for instance, uses moving averages taken over multiple days to stabilize the results. Clearly, the acronymn media doesn’t do this.
That’s my best guess... except for the obvious bias issues!
I have a deep background in science/engineering and worst case analysis. What you present seems pretty clear to me to be an example of sampling bias in favor of Obama. The bias gets harder to sustain as the sampling size gets larger. My guess is that the actual overall average Romney numbers, without bias, would be a couple of points higher.
I’m more interested in the response rate than the sample size. I think all the polls have become rubbish due to low response rate. I’ve been wondering whether Gallup, due to reputation, is getting a better response rate than the others.
Theory 5: Some conservatives (note: not labeled as “Romney voter” purposefully) are deliberately answering opposite their voting intentions to a) skew polls and give Obama some confidence and b) to further erode the credibility of the “Mainstream Media”.
The only poll I would answer truthfully would be Ras. If some media-bought pollster calls me, I’m 100% in Obamugabe’s camp!
I have noticed this also. I think all your explanations have merit, but I rate #2 the most likely. The small lamestream focused polls are deliberately skewing the demographics to better than 2008 Democrat turnout. They know this is wrong, but it’s the only way they can keep their candidate in the lead. This is a deliberate attempt to drive the narrative that 0zer0 is ahead, or at least tied, when averaged with the polls that show 0zer0 behind. They need to drive this narrative to keep their base motivated for any Dem to have any chance in this election and try to avoid 2010 all over again. The high margin of error is their excuse for if it all goes wrong for them.
If 0zer0 is up 2-3 pts in their bogus poll, but there is a 3-4 point MOE, than that explains a Romney +1 to +2 win. Then add the “unexpected” Republican turnout, and you can “explain” the Romney +5 or +6 win. It’s all the lamestream media agenda to favor dems at all costs. They are nothing but an extension of the DNC. The lamestream media doesn’t care about their reputation anymore, or even the fact that they are biased. The big polling companies do, so that is why they are more accurate.
The MoE dimishes in size as the poll samples get larger. The smaller the poll size the larger the potential for inaccuracies.
Anyway, the current RCP unweighted average of ten polls has Romney up by 0.6%. But if we weight by sample by sample sizes, then Romney's advantage goes up to 1.2%
More interesting to me, however, is that when we drop the five polls that lack results from after the 3rd debate, then today's unweighted advantage for Romney goes up to 1.2%, and the weighted advantage goes up to 1.7%.
(I would also like to compute a pooled margin of error for the "meta-sample" -- except that my math skills don't seem up to the job!)
Statisticians will tell you that the larger the sample size, the more reliable the poll.Not to put too fine a point on this but, you really should say that the larger the sample size the margin of error goes down. That may or may not mean more reliability. It does mean that given any other poll structural flaw, as you increase sample size your margin of error within the structure of the poll itself goes down. My main question with all these polls is this: if you get to the end of compiling your results and the internals don't pass the laugh test, you need to audit the structure of the poll. Does that mean you need to always adjust for party affiliation? No. But you should always watch that and make sure in the end what you get falls within the realm of possibility.
There’s no reason a smaller sample size should be biased one way or the other. The chances are very small that all the small sample sized polls are leaning more towards Obama just by chance. More likely it has something to do with methodology. For example, are the polls favoring Obama weighted for a Dem turnout similar to 2008?
Larger sample size = smaller margin of error.
That simple.