Norm and Norma do not exist. This is the first thing worth establishing, because the entire edifice of the system that invokes them rests on the pretence that they do.
That somewhere, in some suburb indistinguishable from the one you live in, two people are living the lives that the guidelines describe, presenting with the markers the frameworks expect, responding to interventions in the ways the evidence predicts, ageing along the trajectories the actuarial tables project.
Norm and Norma are the average made flesh. They are what happens when you take all the data, find the centre, and imagine the person who lives there.
No one lives there.
The statistical centre is a mathematical location, not a human one. It is produced by distributing a population across a measurement and identifying the midpoint. The midpoint is real as a number. It is not real as a person. The person who scores exactly at the mean on every relevant dimension simultaneously does not exist in any actual population, because the dimensions are not correlated in the ways that would be required to produce them. The person with average height does not have average weight and average blood pressure and average sleep duration and average social connection and average stress levels and average genetic risk and average dietary patterns. The averages are averages of different people measured on different things. The person who embodies all of them at once is a statistical fiction.
Norm and Norma are the ideal patients. They present with the expected symptoms. They respond to the standard treatments. They follow the protocols correctly and produce the outcomes the protocols were designed to produce. They are the reason the protocols work—not because real patients are like them, but because the protocols were built from data that described populations that included them, and the protocols were evaluated against populations that described them, and the margins of error were calculated assuming that the people who would use the protocols would be reasonably similar to them.
When the real patient arrives—the person who does not have Norm’s weight or Norma’s metabolic profile or either of their uncomplicated relationship to the interventions the guideline recommends—the protocol encounters a body it was not specifically designed for. The protocol does not know this.
The protocol does not have a mechanism for registering the divergence between the person it was designed for and the person who is presenting. It has a set of decision trees, and the person enters the decision tree at the appropriate branch, and the tree produces its recommendation. The recommendation is the recommendation the tree produces for everyone who enters at that branch.
The recommendation was calibrated for Norm or Norma.
The person is not Norm or Norma.
The recommendation may still be useful. The evidence base behind it is real. The average effect size is genuine. The intervention works for the average person in the population that was studied. The question is only whether the person presenting is close enough to the average person in the population that was studied for the average effect to be a reasonable expectation.
Sometimes they are. Sometimes they are not. The protocol cannot tell the difference.
Norma does not present to the system. This is the further paradox that the system does not fully acknowledge. Norm and Norma, if they existed, would not be in the data that produced the guidelines. The data comes from people who presented to clinical services, who enrolled in studies, who participated in trials. People who are fully functional, managing adequately, experiencing no symptoms that require clinical attention, do not typically present to clinical services. They are not in the trial populations. They are not in the outcomes data. The guidelines were built from data about people who needed the guidelines, not from data about the people who did not.
The person who is the ideal outcome of the clinical guideline—the person who has the condition being managed and is managing it well—is the person least likely to appear in the dataset that produced the guideline. The guideline was calibrated against people who were not managing well, or who were newly diagnosed and had not yet established management, or who had complications that the baseline management had not prevented. The guideline describes what to do for people who are not Norm or Norma because the people who are Norm or Norma are not in the room.
When the person who has been successfully self-managing for years does appear in the room—because they need a referral, because they need a test, because the healthcare system’s gatekeeping requires clinical involvement to access services their condition entitles them to—they arrive in a system that is calibrated for the person who needs managing, not for the person who has been managing. The system is not oriented toward them. It is oriented toward the person in the adjacent decision tree branch.
The aspiration to be Norm or Norma is communicated in ways that are so embedded in the system’s language that it is rarely examined as aspiration. It arrives as standard. The normal range on the blood test result. The recommended BMI. The target blood pressure. The sleep duration associated with optimal health outcomes. The number of steps per day linked to reduced cardiovascular risk. The servings of vegetables. The units of alcohol. These are presented not as what the average person in the studied population consumed or achieved, but as what the person aspiring to health should consume or achieve. The average has been converted, without explicit acknowledgment of the conversion, into a prescription.
The prescription is calibrated for Norm and Norma. It is communicated as if it applies equally to everyone. The person who is not Norm or Norma—whose physiology, whose history, whose circumstances, whose specific configuration of risk and resilience does not match the population from which the average was derived—receives the prescription for the average person’s body and is invited to assess themselves against it.
The assessment typically finds a divergence. Most people are not Norm or Norma. The divergence is experienced as failure or as risk, depending on the direction and magnitude of the departure from the average. The person whose blood pressure is consistently below the normal range is told their blood pressure is low and asked if they feel dizzy. The person whose resting heart rate is lower than average because they are fit is flagged for investigation. The person whose body weight sits outside the BMI category that the evidence associates with optimal outcomes is told they are overweight or underweight, and the clinical conversation proceeds from the divergence rather than from the person.
The bell curve is a description of a population. It is not a description of an individual. This distinction is so fundamental to statistics that it appears in the first weeks of any introductory course in the subject. It is consistently lost in the translation from population data to individual clinical recommendation.
The statement that people with this condition have a significantly elevated risk of this complication is a population statement. It means that in a group of people with this condition, the proportion who develop the complication is higher than in a group without the condition. It does not mean that the person sitting in the chair will develop the complication. It means they are in a group that contains more people who will develop it than a comparable group without the condition. Their individual probability is not the group’s rate. Their individual probability is unknown. It is influenced by their specific physiological profile, their specific management, their specific genetics, their specific circumstances—none of which appear in the population statistic.
The clinical communication of this distinction is variable. The clinician who explains it clearly, who presents the risk as a population tendency rather than an individual destiny, who leaves space for the specific person’s divergence from the average to be relevant to the clinical conversation, is providing genuinely useful information.
The clinician who communicates the population statistic as an individual prediction—who tells the patient that many patients in their situation eventually develop complications, in a tone that invites the patient to hear this as a personal forecast—is communicating something that the statistics do not support and that the patient is likely to receive as more deterministic than it is.
The patient leaves with a number that was a population rate and experiences it as a personal trajectory. The number becomes the expectation against which they assess their own condition. The expectation shapes the clinical relationship. The clinical relationship is now organised around the population statistic, applied to the individual, in ways the population statistic was never designed to support.
Norm and Norma are presented to us as aspirational figures partly because aspiration is operationally useful to the system. The person who aspires to the normal range, who orients their behaviour toward the average outcome the guidelines describe, is a person who is moving in the direction the system is designed to manage. The aspiration produces the compliance. The compliance produces the predictability. The predictability reduces the variation that makes large-scale healthcare management difficult. The system functions more smoothly when its population resembles Norm and Norma closely enough that the guidelines calibrated for them produce reliable outcomes.
The cost of the aspiration is borne by the people who cannot resemble Norm and Norma—whose bodies, histories, or circumstances place them outside the bell curve in ways that the aspiration cannot address, and whose divergence from the ideal is experienced as personal failure rather than as the natural and inevitable condition of human variation.
Human variation is not a problem to be managed. It is the condition of humanity. The bell curve is not a description of the ideal human. It is a description of the distributed reality of actual humans, most of whom are not at the centre, none of whom are Norm or Norma, and all of whom are receiving a system calibrated for two people who do not exist.
Norm and Norma live in the data.
Everyone else lives in a body.
The two are not the same address.
The system has one set of instructions.
It sends them to both.
The Vorpel Foundation