Psephological Concussion

You mean “glaringly obvious” in the sense that it’s glaringly obvious he’s using the old trick of starting the Y axis at a number well above zero to distort the scale of the graph? I’d suggest that “Lemak” might find this link useful, or maybe this one. Something tells me, however, that he’s already well acquainted with the material. He just doesn’t think anybody else is.

Statboi – you’re talking complete and utter smack. What Nasi Lemak has done is widely accepted as best practice – he’s focusing on a segment of the Y axis to show the range of variation. No distortion involved at all – it’s exactly the right way to present the trend that he’s interested in.

Don’t believe me? Let’s ask “Edward Tufte”:http://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=00003q&topic_id=1, whose work you seem to think would be “useful” for Nasi Lemak.

bq. In general, in a time-series, use a baseline that shows the data not the zero point. If the zero point reasonably occurs in plotting the data, fine. But don’t spend a lot of empty vertical space trying to reach down to the zero point at the cost of hiding what is going on in the data line itself. (The book, How to Lie With Statistics, is wrong on this point.)

My advice to you: if you want to cast aspersions on someone else’s professionalism and honesty in future, it would probably be a good idea actually to read the authorities who you cite to. Otherwise, you’re sometimes going to find that they agree with him, rather than you. And that’s embarrassing.

The scale doesn’t mislead much does it? I don’t look at the graphs and think that Bush’s support is approaching zero – the numbers are right there. It’s the consistent trend down, interrupted by a few rally-round-the-chump moments, that draw the eye.

Anyway, I see why a terrorist attack might heighten one’s identification w/ their state, and sympathy with the victims in a kind of “but for the grace of God go I,” but why should a national tragedy necessarily boost support for the incumbent? If Bush’s post 9/11 performance was outstanding in some way, that’s one thing, but the swing in support seems to come before that could be known.

Are we children hiding under the covers wanting daddy to kill the monster under the bed? What if daddy’s an idiot whose monster-abatement strategy proposes setting the house on fire? IOW, could the bounce have gone to any warm body who currently occupied the White House? Clinton?

Or was there some kind of firm hand and steely resolve that comforted, hit the sweet spot of revenge and grace? I must’ve missed that.

How come nobody has thought to ask what the normal pattern is over a presidential first term?

Duh.

Bush’s performance would ‘hit you between the eyes’ rather differently in that (appropriate) context. Look it up.

Tufte says:

But don’t spend a lot of empty vertical space trying to reach down to the zero point at the cost of hiding what is going on in the data line itself.

So? That doesn’t mean that removing vertical space in order to hide what’s going on is perfectly okay.

P 93 The Elements of Graphing Data by Cleveland

“Huff’s presumption is that viewers will not look at tick mark labels and apply the most trivial of quantitative reasonsing.”

“For graphical communication in science and technology assume the viewer will look at the tick mark labels and understand them. Were we not able to make this assumption, graphical communication would be far less useful. If zero can be included on a scale without wasting undue space, then it is reasonable to include it, but never at the expense of resolution.”

Or, ,more simply, get a clue statboi. Wrong audience with which to whine about your poor understanding of graphing data.

To be fair to statboi, the zero point -is- relevant in this graph. Consider if you took the subset of the data between mid-September ’01 and the middle of ’02, and drew that graph with 90% and 70% as the boundaries. What you’d get is a picture approximately like the one linked to, showing a precipitous drop. And yet as this graph correctly shows, mid-2002 was actually a pretty strong point for Bush.

The thing that statboi misses, I think, is that there IS a zero point on this graph, even if it’s not marked with a zero. At 50% approval, Bush has a 0% net positive approval rating. Above that point, he is popular with a majority of the population; below that point, he is unpopular with a majority. It would’ve been misleading to put 70% at the bottom of the graph, because (as we can see) you can go a lot lower than 70% and still be popular. But you can’t go lower than 50% and still be popular. Easy.

If you took this graph and rescaled it all the way down to zero, you’d actually be making it -more- misleading, by making it appear that Bush had that much farther to drop before reaching a crossover point. Not so: the crossover point has been reached already, as the graph shows.

Thanks for the chart, Matt. I read this data as follows:

(i) Every president was in the low to mid fifties at the three year point. Even Carter managed to bounce there for a few months.

(ii) If you were higher than the low to mid fifties 18 months into your first term, you got to the level described in (i) by declining. If you were lower than that 18 months into your first term you got there by improving. No surprises here.

(iii) After the three year point the candidates diverged. Those who would go on to win climbed slowly during their fourth year in office to around 60%. Those who would go on to lose had fallen disastrously by the end of the first quarter of their fourth year to 40%.

(iv) Bush is, per this data, still looking distinctly more like a winner than a loser.

The real question that is important to answer in any statistical analysis whether interocular or not is whether the future or present is different than the past. It could well be that something has fundamentally changed about how we evaluate Presidents. I don’t think so, but it is interesting to not the GOP started making this argument when Bush went below 70.

Second thoughts: I suspect that the IEM numbers (which are for the vote-share market because the winner-takes-all market hasn’t opened yet) are picking up the effect of Nader entering the race rather than implicit movements in the Kerry/Bush share.

I saw that Iowa comparison chart (at Instapundit!). I know little of psephological analysis, but would Reynolds’s conclusion (that Bush gathered strength from the point where Kerry emerged as the likely nominee) be reasonable?

If so, prhaps this indicates partly that the election may well be decided by how the electorate feels about its security in the light of the performance of the incumbent and the stated strategy of the challenger in the “war on terror”.

Oooh, fame (of the barely anonymous sort). Anyhow, I didn’t want to post any interpretation of the graph in the original postings, but here goes: the key thing here seems to me *not* the absolute level that the approval ratings have reached, but rather that this administration has never had, at any point, steady increases in approval, nor has it had broadly stable approval ratings except perhaps at the very beginning. The ratings will, surely, at least stabilise a bit, but I’ve been saying that since the mean was about 65% and it hasn’t happened yet.

WE should form a brown shirt party and go around atacking male St Bernards who want to marrry, or something ridiculous.

OOPs! Just a thought.

WE should form a brown shirt party and go around atacking male St Bernards who want to marrry, or something ridiculous.

OOPs! Just a thought.

One other remark for statboi. Tufte, in his classic _The Visual Display of Quantitative Information_, does disapprove of crossing the ordinate of a time series graph at a point other than the zero, because this can lead to confusing the crossing point with a zero point.

However, his proposed solution is not to include tick marks all the way down to the zero (apart from anything else, this would be mathematically impossible where the ordinate is a logarithmic scale).

Instead, he recommends truncating the axes before they have an opportunity to cross, leaving them floating in space below and to the left of the data, respectively. This conveys the correct impression while not wasting space.

Sadly, many graphing utilities (such as the ubiquitous MS Excel) are not well equipped to do this, but that’s not the original poster’s fault. statboi is not only making a fuss about a small matter, but he’s making it about the wrong small matter.

FWIW, the Executive Director of Democrats Abroad reports: “In January 1980 Carter led Reagan by 62-33% but lost in November by 10 points. In October 1983, Mondale led Reagan by 50-44% but lost 59 to 41%.” I envy those who have public sentiment figured out.

To tie this into the thread on the “Book of Revelations(sic)”, polls suggest that about 2/3 of the American people believe in the Second Coming of Jesus.

Ed Zeppelin wrote:

“Clinton got over 50% in 1996.”

Nope. 49.24%.

If you are interested in what I would call a “fundamentals” approach to the question, rather than arguing about graphs, take a look at this post
which uses standard political science arguments to predict that — if the American economy grows as most economists predict — Bush will defeat Kerry by 59-41 in the two party vote.

I’ll be updating these predictions at least once a month, by the way.

Note that I made the prediction early in March, before Bush retook the lead.

I glanced at “Nasi Lemak”‘s chart and the discussion accompanying it, but saw no insights from political science. But then I’ve been out of the field for many years, so perhaps I missed something.

Those interested in my previous predictions can look in my November 2002 archives.

Archpundit – That’s a fair question. Briefly, I am skeptical about the thinking behind the models, because they appear to have been constructed by experimenting to see which measures give the best fit. Unfortunately, that will, if you fiddle enough and have small data sets, always appear to fit the data well.

As for making my own argument more mathematical, I could do that but don’t think it worthwhile, given the poor measures of some of the important variables and small number of cases.

I have done longer critiques of those models in the past and will probably do one again at my site before the election. For those who want a hint, just ask yourself how many elections the models are tested against, 10 maybe?

I think that this election will be decided by events occuring between now and the election. Both campaign events and events in Iraq and elsewhere. Trying to figure things out by measuring trends is delusory. (Yes, I mean you!) However, this graph does show me that Bush is vulnerable.

A friend of mine thinks that Osama will be captured at the appropriate time before the election. If Bush manipulates events successfully, he will probably win. If things swing out of his control, he won’t.

My feeling is that Bush-Rove look at excess approval ratings as uninvested capital. If Bush popped above 60% he’d probably do something unpopular on his agenda to bring things down to 52%, which is where he wants to be.

This thread does exemplify CT comments’ two worst traits: troll-driven threads, and second-order methodological wonk discussions. Let’s give a round of applause to statboi for her sterling red herring.

I think that this election will be decided by events occuring between now and the election. Both campaign events and events in Iraq and elsewhere. Trying to figure things out by measuring trends is delusory. (Yes, I mean you!) However, this graph does show me that Bush is vulnerable.

A friend of mine thinks that Osama will be captured at the appropriate time before the election. If Bush manipulates events successfully, he will probably win. If things swing out of his control, he won’t.

My feeling is that Bush-Rove look at excess approval ratings as uninvested capital. If Bush popped above 60% he’d probably do something unpopular on his agenda to bring things down to 52%, which is where he wants to be.

This thread does exemplify CT comments’ two worst traits: troll-driven threads, and second-order methodological wonk discussions. Let’s give a round of applause to statboi for her sterling red herring.

I think everyone is missing the point here by trying to project forward to 2004-11-02. If the numbers tell us anything, it’s that this administration’s future poll numbers are _less_ predictable than those of recent ex-presidents.

Why? Because, as Nasi Lemak observes above, the data do not probe GWB’s stable “baseline” support at all; they only define a lower bound for it at 50%. What they show is that (1) running away on 9/11, starting the wrong war, and shaving the Iraqi butcher are each worth a discontinuous boost, and (2) the Shrub has been losing support at 2% a month (comparable to his father’s slide, and, barring Watergate, about as fast as polls can fall) for _all the months he’s been in office_ except the initial honeymoon and the rally-round-the-flag spikes.

What these numbers must be telling Karl Rove (who is surely reading them without hazy Tuftean digression) is that his man has _only one proven way to win public approval_. In other words, that the crucial election-day number can be swayed _only_ by one more national wake-up, and that the November extrapolation without one is in the unplumbed upper 30s. This is _emphatically_ not a line of reasoning I want haunting the corridors of power through a long hot foreign-policy summer.