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View Diary: Beyond the Margin of Error: When Polls Fail, or Why Elizabeth Warren Will Dash GOP Hopes (104 comments)

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  •  I see what you're saying now. (0+ / 0-)

    You are assuming 'partisan lean' without modifier is comparative partisan lean, I am assuming 'partisan lean' without a modifier is absolute partisan lean.

    So I will try to always use a modifier in the future for clarity!

    •  I would suggest to you (0+ / 0-)

      that disregarding the median will confuse the issue greatly. It would have meant that every state except Minnesota was Republican-leaning in 1984, which is patently untrue, given that the median state would have had something like 13% margin for Reagan.

      And now, getting back to the question of the effect of a partisan lean: How much of a lean do you think is necessary to have a partisan effect? I would say without much hesitation that if McCaskill loses to one of the bozos running on the Republican side, it will be strictly because of a strong Republican lean in Missouri. If the same candidates were running in Wisconsin or Iowa, McCaskill would probably win by at least 10.

      A further remark would be that if things go so badly for Romney and the economy has a sudden upturn, such that Obama loses by no more than 2% or so in Missouri, McCaskill will probably win. But in that case, Obama will be winning by plenty - probably at least all the states he won in 2008 except Indiana, plus Arizona.

      Formerly Pan on Swing State Project

      by MichaelNY on Mon Jun 18, 2012 at 04:14:17 PM PDT

      [ Parent ]

      •  The effect (1+ / 0-)
        Recommended by:
        MichaelNY

        I assume you are referring to the effect discussed in this diary?  That is, that the difference between the margin in the polling average and the actual results is a function of the partisan lean of the state in close races.  

        You can see how much of a partisan lean is necessary to see this effect in the second graph of the diary.

        At Obama = 50% (absolute margin =0, relative margin R+7) the effect is zero; this is where the purple line crosses the x-axis.  

        A point or two away from 50%, the effect is still very small and not likely to be noticeable, especially compared to other noise.  

        At Obama = 53% (absolute margin D+7, relative margin=0), the effect, on average is that the election margin is +1 for the Democrat compared to the polls.  But because of other noise, the range we would expect to see for an individual contest is from D+6 to R+4.

        At Obama = 57% (absolute margin D+14, relative margin D+7) the effect, on average is that the election margin is +3 for the Democrat compared to the polls.  But because of other noise, the range we would expect to see for an individual contest is from D+8 to R+2.  This is getting more noticeable.

        At Obama = 62% (absolute margin D+22, relative margin D+15) the effect, on average is that the election margin is +5 for the Democrat compared to the polls.  But because of other noise, the range we would expect to see for an individual contest is from D+10 to D+1.  This is the point, in deep blue states, where an effect has been noticeable 95% of the time in the past.

        The effect goes the other way too; switch out parties in the above descriptions and you're got the right numbers for the magnitude of the effect.

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