"Zogby said that Tuesday was a really good day for Kerry in which he polled at +5. That day should be rolling off in tommorow's sample. That means Kerry would have to poll like +6 or +7 in today's sample. It was kind of like last weekend when Zogby came out and admitted that Bush had two day samples where he lead 50-43 and 49-46, yet Bush only had like a 2 or 3 point lead in the poll. Zogby's math just doesn't add up."
Let's go inside the numbers, shall we?
These were the Oct. 23 and Oct. 24 numbers. On the morning of October 26, Zogby reported the race as Bush 49, Kerry 46. To get this average, the October 25 result had to be Bush 48 ((50+49+48)/3=49), Kerry 49 ((43+46+49/3=46).
On the evening of October 26, Zogby reported that Kerry won the night by five points. On the morning of October 27, he reported the race as Bush 48, Kerry 47. Taking these two facts together, the Tuesday result had to be Bush 47, Kerry 52 -- if Zogby is telling the truth. The reason is because the Saturday sample dropped off, and 47 is the number that, when added to Sunday's 49 and Monday's 48, results in the three day average of 48 reported on Wednesday morning.
But the problem is that Kerry couldn't have gotten 52 on Tuesday night. To be at 47 on Wednesday morning, Kerry had to score 46 -- not 52 ((46+49+46)/3)=47). Something is already fishy here, but let's assume he scored 46 and continue.
On the morning of October 28, Zogby reported the race as Bush 48, Kerry 46. Doing the math, Bush scored 49 on Wednesday ((48+47+49)/3). Kerry scored 43 ((49+46+43/3=46).
On the morning of October 29, Zogby reported a 47-47 tie. This is where it gets even more screwy. To poll only 47, Bush polled only 45 on October 28 ((47+49+45)/3=47). Kerry polled a whopping 51 (after polling only 43 the night before) ((46+43+51)/3=47).
So, here is what his daily numbers look like for last six days -- if he is accurating reporting the numbers for last weekend:
Bush 50 49 48 47 49 45
Kerry 43 46 49 46 43 51
If anyone thinks that these numbers accurately reflect what has actually been happening in the race the last six days, you deserve to get stressed out by Zogby polls (or, for that matter, other tracking polls). If this isn't enough to convince you, look at Zogby's state by state tracking, which is even whackier and subject to even wilder swings. These polls are little more than statistical noise -- not real polls like Gallup, Opinion Dynamics, or Battleground.
Right on
Kerry was + 5 on tuesday but yet Bush was still up 2 on thursday..makes no sense...ten point swing in MI? Kerry up in CO?..Pllllllllllllllllllllease
I think you are reading too much into what Zogby says. He could have been talking about independents, or difference between R and D, etc. I don't think you could do assume a simple set of numbers to get 49%. For example, you average 48, 49, 50. You can have a wildly different set of numbers like 60, 45, 45 to get 49%. So if 60 rolls off, then the tracking numbers change by a big amount.
But I agree with you that Zogby is full of shit. I think we should all throw out Zogby's #'s, and concentrate on reall polls like Gallup and Battleground #'s.