Monday, November 30, 2015

It doesn't really matter who's winning now

If you like politics, then it's fun/interesting to watch the horse race in the Republican primary (the Democratic primary lacks the same drama and has played out as predicted so far). But, if recent history is any guide, I wouldn't give the current polls a lot of value if you're trying to figure out who the 2016 nominee is going to be.

Looking at the last four contested primaries, the eventual nominee hadn't moved to the top of the national polls until January or February.

In 2004, eventual Democratic nominee John Kerry was behind in the polls until late January, 2004 - several days after the Iowa primary.
In fact, at this point in the year, and after this point in relation to the Iowa caucus, Kerry was in 4th place.

In 2008 the polling was similar on the Republican side. Two months before the Iowa caucus, McCain was in third place, and with less than a month to go, he would drop to 5th. Here again, he wouldn't become the front runner until a week after Iowa, and 3 days after New Hampshire.

The 2008 Democratic primary polling looked somewhat similar to the way it looks this year, with Hillary Clinton sitting comfortably ahead of the field, but then at around this point (two months prior to the Iowa caucus) Obama began to move up steadily in the polls. He didn't become the front runner in National polls until mid February, nearly 6 weeks after Iowa.

And of course, much has been made about the difficulty Romney had in 2012 consolidating the support of Republicans. After leading for much of the early part of the campaign, Romney lost the lead 5 times between June 2011 and March 2012 to 4 different opponents. He did lock down a lead in the national polling until the last day of  February, nearly two months after Iowa.

The 1992 Democratic primary was also late to develop. Back in 1992, Clinton didn't finally take the lead until early March (a few weeks after Iowa), and the person he was behind prior to that wasn't even in the race.

Of course, this is all in contrast to 2000 a year with no incumbent candidate and a year when both eventual nominees were front runners before they entered the race, and remained front runners to the end. Which is how the Democratic nomination is looking this year.

Similarly, in 1996 Dole led the Republican primary polling from early November, when he regained the lead from Colin Powell after Powell announced he would not run, until the end.
Will Trump or Clinton in 2015 be more like Dole, Bush or Gore in 1996 and 2000, or more like Giuliani and Clinton in 2008? At this point the only thing we can say is that the polling up to now doesn't really mean much.

Wednesday, November 11, 2015

We really could all die

Clearing out the old blog post ideas here. Back in 2013 (I know, I know) Ezra Klein had a story on global pandemics that oddly didn't mention the worst disease to come along in modern times, by which I mean AIDS. It's odd, because HIV in many ways contradicts one of the key ideas in the article.
Diseases face a choice between spreading easily and being severe. If a disease is too hard on its host, killing quickly, it can’t spread. If it’s too easy on its host, it doesn’t much matter if it spreads. 
But HIV spreads pretty easily and is (or at least was until the "cocktail" for treatment was developed) as severe as can be imagined. If you were designing a disease to wipe out a large portion of the population, HIV would provide a pretty good model for two key reasons.

The first is that victims don't actually die of HIV. They die from something else because their immune system is so weakened that an opportunistic infection (like thrush and Kaposi's sarcoma) can spread and eventually cause death. This enabled HIV to hide for several decades as patients were assumed to have died from the other infections. Even after HIV made it to the United States, it took a decade to detect it.

The second reason is that it has a long incubation period. Klein was right that a disease that kills too quickly can't spread, but one that kills nearly 100% of the time can still spread - as long as it does so slowly. And the median incubation period for HIV is 10 years. The saving grace, if you wish to call it that, of HIV was that it was an STD, which significantly slowed down the rate at which it could be spread.

But imagine if HIV was a vector-spread disease like malaria, or could be transmitted via droplet spread or what if it had been airborne. In other words, if HIV had a Basic Reproductive Number that was closer to that of measles or whooping cough it would have spread very far and infected many many people before we even knew there was a new disease on the loose. And it took us nearly 15 years from HIV identification to effective treatment, during which time the disease continued to spread.

Another thing to consider is a disease that alters the hosts behavior like toxoplasmosis does. The life cycle of Toxoplasma gondii, the parasite that causes toxoplasmosis, requires the disease to be passed between rodents and cats. Rodents infected with the disease will have their behavior modified so that they are less fearful of cats and so that they behave in ways that are unsafe, thereby increasing the chances that they will be eaten by a cat and continue the cycle. Even humans infected by the disease have been shown to be involved in a higher rate of car crashes and other risk-taking related deaths, indicating that their behavior has been changed as well.

Imagine an HIV that changes peoples behavior, making them engage in more sex and/or riskier sex. Such behavior could increase the transmission rate considerably over what was observed. Or imagine a flu-like disease that makes someone become more gregarious and outgoing during their peak contagious period, allowing them to come into contact with more people and spreading the disease more quickly.

It is unlikely, but a disease really could cause a world-wide pandemic that threatens human civilization. What would such a disease look like? It would be a disease, like HIV, with a long incubation period and low survivability rate, and one that masks it impact and is hard to understand, but with a higher transmission rate more like the measles. Such a disease could very well create a movie-like disease-based pandemic that would infect and kill 5% or 10% or 20% of the world's population. And how large an infection would it take to strain the civilization that we have now? Probably lower than 20%. Like I said, it's unlikely, but then so was HIV.

The scary thought is not that something like the AIDS crisis could happen again, but that perhaps, as bad as it was, we got lucky.