Category: Science

Methodological Problems in Epidemiology

As much of the world looks to slowly ramp down COVID-19 isolation measures, it remains unclear whether this global social experiment should be considered wise or foolish. The prevalence of infections is < 1% in every country in the world except the microstate San Marino. This is better than projected by most models, and could be interpreted as a success for isolation, an overestimation of the virus's infectiousness, or a natural seasonal effect. This question is not resolvable insofar as it depends on the counterfactual of what would have happened if isolation was not imposed. As mentioned in the last post, spread to 60% of the population with millions of deaths was never realistic. That alarmist scenario relied on a naive application of epidemiological models that have poor predictive ability. Using an SEIR model with the estimated parameters for COVID-19, one indeed gets a grim picture. Yet if one were to insert the parameters for seasonal influenza (R0 = 1.3, avg. incubation period = 2 days, avg. duration of infectiousness = 5 days, mortality rate = 0.1%) into the same model, you would have over 40% infected and 150,000 fatalities in the first year, far more than what occurs in reality. The reproduction rate of a disease depends not only on the duration of contagiousness, but also the likelihood of infection per contact (secondary attack rate) and contact rate. These last two are highly variable by region, social structure, and perhaps even individual physical susceptibility.

Conventional compartmentalized models have poor predictive ability for seasonal influenza, as they do not account for other factors besides herd immunity and isolation that could slow the spread of disease. A Los Alamos study was able to create a model with parameters that fit to past seasonal data and should hopefully have predictive power for future seasons. Such an approach, however, is useless for novel pandemics. As the authors note, these models are all highly sensitive to choice of prior parameters, but we cannot know these until after the epidemic has run its course.

The problem of predictive modeling is exacerbated by the poor quality of public health data, which is often woefully incomplete or inconsistent, with categorizations often driven by policies or other unscientific criteria. Public health systems do a better job of recording the number of infected than they do for those exposed or recovered. Even here they are limited to those who seek medical treatment, and often diagnoses are made by symptoms rather than definitive tests. Cause of death on death certificates is driven by bureaucratically imposed standards. Even in scientific studies, researchers classify subjects according to one or another cause of death, and treat comorbidities as risk factors increasing the chance of death by the primary cause. It would be more rigorous to acknowledge that there is not always a single cause of death, and instead to treat comorbidities as contributing causes by factor analysis. This would let us know the mortality contribution of each disease to the population, but it would remain generally impossible to give a single “cause of death” for each individual.

Some parameters of COVID-19 are fairly well known at this point. The infected are contagious from 48 hours before showing symptoms to 3 days afterward. The secondary attack rate is surprisingly low, only 0.45% (compared to 5%-15% for seasonal flu). Thus the relatively high R0 is attributable not so much to high contagiousness, but to the longer duration of contagiousness, especially while presymptomatic, so that infected people have more contacts while contagious than seasonal flu victims would. The 2009-10 H1N1 pandemic, by contrast, had a secondary attack rate of 14.5%, yet it infected 61 million out of 307 million in the US, just under 20%. It is implausible that COVID-19, with its much lower attack rate, could ever attain a comparable prevalence level.

Why, then, are the death statistics so much higher than would be suggested by the low infectiousness and low prevalence? On the one hand, many jurisdictions, notably New York, have decided to include so-called “probable” COVID-19 related deaths, and most public health data includes no serious attempt to account for comorbidities as causal factors, though they occur in well over 90% of fatal cases. On the other hand, the increase in deaths versus last year in many areas greatly exceeds even this high count, so it could be argued we are undercounting COVID-19 fatalities. The problem here is that many of the excess deaths could be caused not by COVID-19 per se, but by the overloading of medical facilities, resulting in less than immediate critical care. Some of these excess deaths might even be caused by the quarantine measures, as diagnostic and non-emergency medical visits have been cancelled.

It would not be uncommon for the number of deaths to be revised upward or downward by a large factor retrospectively. A year after the H1N1 pandemic, a study suggested that the deaths attributed to H1N1 ought to be revised 15 times higher. Whether H1N1 deaths were undercounted or COVID-19 deaths are overcounted remains to be seen, and is unlikely to be resolved, given the problems of data and methodology we have touched upon.

The truly frightening thing is that major public health policy decisions are made on woefully inadequate data and modeling, which will likely be radically revised after each pandemic passes, and the moment for decision-making is past. Public health officials will always err on the side of caution, but as we have noted in the previous post, this is not practicable for an indefinite period of time. At some point we must be willing to poke our heads out of our caves and assume the risk of living.

After all, as recently as the early twentieth century, people went about their business even while living under the threats of smallpox, polio, and measles, any one of which had higher infectiousness and fatality rates than the current pandemic. By objective criteria, there is nothing exceptional about COVID-19 as an infectious disease. What is exceptional is the post-WWII belief that life should be free from deadly risk, enabled by technological means to perform many service economy jobs remotely.

The Aesthetics of Psychics

Is there such a thing as being psychic? After a century of failure to validate any claims of telepathy, clairvoyance, fortune-telling, and the like, it might seem daft even to raise the question. Yet this would be to ignore the reality from which the modern notion of “being psychic” emerged. There have always been people who are acutely sensitive to nature and to other people. They may pick up on nearly imperceptible signals and are attentive to the spiritual or mental states of others, or even that of nature, being raised to ecstasy or troubled with pain. Though there might not be anything properly supernatural about this, it is far from an ordinary ability. This is something real, like having rhythm, but there is a temptation to make this into something intelligible, thereby falsifying it.

When you try to make “being psychic” something intelligible, like telepathically receiving words or images, you take whatever was real about such sensitivity and turn it to something false. The modern notion of “being psychic” incoherently flounders between nature and supernature. Is it a natural power? If so, then it would be something intelligible under our notions of physics and biology. It would be something measurable, testable, with some genetic or molecular basis. Is it something beyond our nature? In that case, there is no sense in speaking of someone “being psychic,” as the supernatural phenomenon belongs to something other than the person. When you try to make it something intelligible, following a fixed rule, you make it into something that will be proven false, since you have denied what was real about it.

Do the empirical falsifications of psychic claims mean there is no such thing as psychics? Only in the sense of having determinate powers following some fixed rules. If we return to the original conception of someone who is sensitive or in rapport with his fellow creatures, or with the reality that underlies them, we can no more say that this is unreal than that there is no such thing as having rhythm. A person who “has rhythm” goes by feel, knowing when to speed up, slow down, hesitate, or keep two times at once. If he were to try to write this in musical notation, or to turn his gift for improvisation into a fixed set of rules, he thereby would falsify the gift, producing something other than his art.

Ancient cultures recognized that certain people had a sensitivity to nature, a rapport with the fundament of reality. This was manifested as a sense of harmony, balance or peace. In cultures with more ethical conceptions of the Divinity underlying nature, those who had a rapport with goodness, wisdom (not intelligence) or justice might be trusted to speak for God. Again, attempting to render this intelligible falsifies it. We intuitively apprehend, for example, that it is good and beautiful to save life, while it is evil and ugly to murder. If you try to rationalize it, saying that it is to your biological advantage or in your enlightened self-interest to abstain from murder or to prefer a society where people aren’t allowed to go around killing each other, you have taken the virtue out of virtue. You are saying that the only reason you don’t kill is because it is not expedient to kill, which is hardly distinguishable from the soul of a murderer. The assumption that reality is always improved by making it more intelligible is repeatedly falsified in art, morality and religion. Those who are wedded to this assumption will have a low appreciation of these aspects of human existence.

Psychics represent a segment of the population who are not ashamed of their subjectivity, and recognize it as a basic reality that needs no extrinsic justification. They go astray, however, in modern society, starting in the nineteenth century, when some psychics thought they needed to make their abilities into something objective, in order to be respectable. This naturally failed. If we are surprised at why psychics persist in their self-belief even after empirical falsification (setting aside the shameless charlatans), we must recognize that they still retain some sense of subjectivity as a value in itself. Indeed, without such self-belief, their aesthetic sensibility would be impossible. An artist must have confidence in every stroke, every beat, or his work will lose the quality of art, making it something too labored, too constructed. Those who lack the ability to feel a Negro spiritual well enough to sing it are incompetent to judge this area of existence. Instead of looking down upon the lack of technique or understanding, they should look up to the noble genius that reveals a glimpse of deepest reality, if only as a flash to be seen, not understood.

Some will dismiss this as obscurantism, but even the most plodding intellectual endeavors in science and philosophy are subservient to this aesthetic desire for insight. Without this, no one could take any joy from his work. Scientists themselves do not criticize the idea that Truth is a positive value to be sought. The worthiness and nobility of their endeavor is something presupposed, and any attempts to justify science in terms of expedience, i.e., for its technological and economic benefits, reduce it to something unspeakably profane and bourgeois. No one could revere a science for such mundane reasons. If it is shameful and falsifying to rationalize scientific pursuits, let us not rationalize the overtly aesthetic.

Everything Is Impossible

Suppose I described a tree to someone who had never seen anything like it. I might say it was a giant creature with countless sprawling arms that never moved, and its body was full of intricate vessels that extracted water from the ground imperceptibly. Most fantastic of all, it had the power to transform light and air into its food, and grew to its great size without taking its bulk from the earth or any other solid thing. Nonetheless, its body was rigid, pound-for-pound stronger than steel, yet lighter than water.

The person being told this might be forgiven for taking this as a tall tale or myth, and the same is true for any natural object. Everything seems impossible or fantastic if we never experienced anything similar. If you saw nothing but cosmic dust, you might never imagine that there could be such a thing as a star. If you saw a barren planet, you might never guess that there could be such a thing as life. If you saw only bacteria, you might never deduce the possibility of more complex organisms. We are able to explain the complex in terms of the simple only after the fact. We have a poor record of determining in advance what is possible or impossible.

If all you knew was physics, you likely would not be able to derive much chemistry. Anything beyond the hydrogen atom is computationally problematic. The few unknown things we have been able to predict are mostly simple structureless entities like fundamental particles and black holes. Everything else comes as a surprise to us. No cosmologist or astronomer anticipated the existence of quasars or pulsars. As with most new things, we first observe them and then try to explain them.

After a long history of discovering things thought to be impossible, if they were ever imagined at all, we should realize how unreliable it is to claim that something is impossible simply because it is outside of our experience. Everything is impossible when abstracted from experience. It is only familiarity that makes these impossible things no longer fantastic.