Category Archives: Global Health

The wikipedia pithy definition is: the health of populations in a global context. https://en.wikipedia.org/wiki/Global_health

Performing health equity: A repeat prescription from yesteryear

In a recent paper in the International Journal for Health Equity, Berenson et al. deliver a hopeful vision of a world better able to take advantage of SDH research. Had the article been published in 2015, it would have landed in a world positioned to take full advantage of the prescription. Unfortunately, the very value frame that supports SDH interventions has fractured. They note this in the lightest way possible, citing a paper by Woolf et al. as evidence of “adverse political environments” for SDH. This characterisation completely undersells what Woolf et al. actually observed — a complete ban, a dismantling, of any research on SDH-style categories: equity, race, diversity, and inclusion. Woolf et al. provide what is close to a complete rebuttal of the point Berenson et al. seek to make.

One of the strongest conclusions from the authors is that “SDH researchers must aim to create and cultivate policy windows of opportunity by being active protagonists…” This assumes at least a world with something approaching shared values, not a world in which “social determinants” are not simply contested but openly reviled and its advocates cast as the enemy — where your notion of fairness is an attack on our cultural values, where your racial equality is advocacy for our genetic and cultural replacement. By their own adopted framework (Kingdon), policy windows rely on a conducive political context. That cannot be created by researchers and has not existed for over a decade! The current political context is not simply unconducive, it is actively hostile. If “cultivating policy windows” — something like a horticultural endeavour at the South Pole — were the solution, then climate regulation would have been resolved, and abortion laws would be universal and rights-protecting, but they are in retreat.

Berenson et al. warn against research that risks being too “technocratic and detached from real-world constraints”, that offers “descriptive documentation of inequities” without “confronting the interests and institutions that benefit from the status quo.” They will say, rightly, that they are not naive about politics — that they explicitly concede research alone cannot overcome entrenched power, and devote an entire section to asking whether the problem is politics rather than research conduct. All of that is true. But notice what the concession does in their hands. They file it. Then without any apparent guile or appreciation of irony, they propose a five-point technocratic corrective. What is needed, they say is more methodological pluralism, more multisectoral collaboration, better communication, reformed incentives, stronger “brokering institutions.” These echo the calls made in the health policy and systems research literature for at least the last fifteen years — including in several of the paper’s own citations, e.g., Rasanathan & Diaz 2016.

The paper is at its core an advocacy piece playing to an audience of the like-minded. As with so many pieces from the last twenty months, which have come out of a loose coterie of global health scholars, civil servants, philanthropists, and diplomats, it fundamentally preserves a shared delusion of global order (or its complete irrelevance) and the insights of yesterday’s science conducted under the aegis of that order. They want to preserve the findings as if they are real, but not the shared value system and international human-rights framework on which those findings — and their policy relevance — are contingent. That, finally, is the more interesting question the paper never asks: not why its fifteen-year-old prescriptions haven’t worked, but whether those contingent truths can ever reach beyond the frameworks that made them possible.

Berenson et al. call knowledge and science “a crucial bulwark to combat forces arraigned against solidarity.” But a bulwark is a defensive structure. It only matters if you still hold the ground behind it. And the ground — the shared value system, the international human-rights framework on which every one of their findings depends for its meaning — is precisely what is being overrun, and they do not seek to protect. This is the paper’s absurdity. Until universal values and rights are put back into the intellectual core, prescriptions like this one are not merely ineffective, they are complicit. They sustain the fiction that the problem is technique rather than the loss of the framework that made the technique meaningful. They keep wanting to refill the gas tank after the bandits have stolen the engine.

Global heating isn’t important–if you’re not suffering.

In the last weeks of June, Europe experienced a heatwave that broke temperature records from France through to Hungary. The heatwave combined high daytime and nighttime temperatures with high humidity. The result was more than 2,000 excess deaths in France alone.

The third heatwave of the European summer has started.

I have been fascinated by the political and technocratic response to the heatwave because, rhetorically at least, this summer has broken through the background hum of climate change conversations. There is a sense of urgency that I have not heard before. “Panic” is probably too strong a word, but governments are clearly worried. Will Europe be liveable in summer in 10 years time?

Having grown up with hot Australian summers and no air conditioning, I was familiar with the routine. Windows open at night to cool the house. Curtains and windows closed during the day to prevent it heating up. Fans helped. Evaporative cooling only worked if the humidity was not already too high. If it was too high, it didn’t feel like you were cooling, it felt like a sauna.

Where I now live in Europe, domestic air conditioning is not permitted, and the Australian strategies only worked partially in my apartment. Before the heatwave began, the internal wall temperatures were in the low 20s, by the end of the heatwave they were around 28.5. The thermal mass of the building had increased. The concrete and steel had absorbed the rolling heat of the day and radiated it out at night. Sleep was late in coming, patchy, and uncomfortable.

The thermal mass problem tracked something a colleague of mine at icddr,b and I had found in slums in Dhaka, Bangladesh. We had placed temperature data loggers in people’s dwelling and captured the rise and fall of temperature and humidity during the day and night. The construction materials were essentially tin and concrete. A tin roof and tin walls became an oven during the day, but cooled rapidly at night (low thermal mass). A concrete roof and concrete walls (high thermal mass) meant that the building’s internal temperature didn’t rise rapidly during the day, but nor did it cool rapidly at night. The concrete smoothed out the temperature variations, but in the absence of active cooling, it eventually rose to the average ambient temperature.

This is the challenge that Europe faces in a world of much hotter summers. Standard passive cooling techniques will get you only so far. Shade to avoid the direct rays of the sun or solar reflectance (albedo) surface to avoid the impact of direct exposure helps. High emissivity surfaces that radiate heat outwards in the cool of the night. Insulation (thermal resistance) to prevent the heat penetrating. Evaporative cooling if humidity permits and water is available.

In summers of regular heatwaves, however, these techniques are limited. Passive cooling can delay equilibrium, but it cannot overcome it. Eventually the thermal properties of the buildings catch-up. And it is difficult to design the building that sheds heat and never captures heat for a scorching summer, but retains and doesn’t lose heat in the winter. All of this assumes that there is even an option to make massive design changes. The vast majority of European housing stock was built with winters in mind, not summers. The oldest buildings, those that give the historic beauty to European cities, have poor thermal properties, and structural changes to them are heavily restricted by conservation laws.

If one cannot rely on passive cooling, then active cooling becomes the fallback. Historically, there have been very low rates of air conditioning in Europe compared to the United States. The latest heat wave, however, has opened discussion about allowing those in “genuine need” to install air conditioning. This, in itself, opens a can of worms. Who has genuine need? Who will pay for the active cooling for those who need it but cannot afford it. The elderly and those with chronic health conditions are often most vulnerable to heat stress. As groups of people, however, they tend to have less disposable income for the purchase and installation of active cooling. Unfortunately, in a continuous heat-stressed environment, everyone will be in need of cooling.

Widespread European air conditioning will also carry at least two unintended consequences. The first is that air conditioning needs manufacturing and maintaining, and power to run it. This will inevitably have greenhouse gas-production issues for a world that desperately needs to reduce greenhouse gas emissions. The second is that, if one is cooling the inside of a building, one is inevitably dumping heat into the outside. And it is slightly worse than that, you cannot move heat from inside to outside a building cost free, you must generate some additional heat to do that. Large scale air conditioning in cities can raise the external air temperature between 1 and 2 degrees, and it creates a feedback loop, because additional internal cooling is needed to overcome the increase in the rising external heat. The consequence for those who do not have air conditioning (those without “genuine need” or those without homes) is that they will experience even more extreme heat waves so that others may suffer less.

Will Europe be liveable in the summers in 10 years time? It really depends on what you mean by “liveable”. The dead trees I have seen– already unable to survive a June heatwave–do not augur well (see the related article on an iconic English oak tree). Passive cooling will help, but as the thermal mass argument demonstrates, it will be insufficient–the second law of thermodynamics prevents it. The answer Europeans seem to be reaching for is air conditioning–for those who can afford it. The heat it dumps outside falls on those who cannot, just as the emissions it produces fall on everyone, everywhere, including places already less able to cope. Widespread air conditioning does not solve Europe’s heat problem. Change nothing about how we live, and shift the cost onto those with the least capacity to bear it.

A New Global Health Architecture: Maximising Health Returns

There have been a number of opinion pieces, resets, and declarations on what is needed in a new Global Health Architecture. These have been authored by diplomats, former Prime Ministers and Presidents, Multi-lateral agency staff and former staff, Philanthropies and peak bodies on what is needed in a new global health architecture. They have appeared in prestigious peer reviewed journals, on corporate websites, and here, I have attempted to synthesise the core messages and draw them together into an aggregate position that can help national governments action some of the ideas.

It starts with the contemporary global health landscape, which is increasingly defined by structural fiscal contraction, evolving geopolitical priorities, and the imperative to sustain health systems performance under conditions of constrained financing. In this context, legacy colonial models of development assistance—characterised by externally driven priorities, fragmented delivery channels, and open-ended commitments—are no longer fit for purpose. A transition toward more efficient, sovereign-aligned frameworks can deliver health at scale across well segmented population groups.

At the center of this transition is a reassertion of national sovereignty. Low- and low-middle income countries have historically been analysed through the lens of deficit-based models—most notably income, poverty and other World Bank style development indicators. In a context of increasing financial constraint and projected stagnation or decline in economic growth, that approach invites systemic failure.

A better alternative is an analysis of countries through the lens of asset-based models and indicators. This shift allows for a reorientation from needs-based allocation towards strategic engagement, in which financially flexible partners align with nationally defined priorities to co-develop fully costed health pathways. Such pathways provide end-to-end cost visibility, improving efficiency and accountability and enabling the precise calibration of health investments against projected returns. The well-established link between health improvement and economic productivity can be operationalised as part of national investment cases.

This reorientation will motivate a shift away from traditional sovereign lending, with its associated conditionalities, as the dominant financing modality. While sovereign lenders have played a critical role in expanding access and supporting system development, their balance sheets are increasingly constrained. Capital markets offer emerging mechanisms to complement sovereign financing in targeted areas where risk can be appropriately structured and priced. Through structured asset-pooling within and across countries, these mechanisms can enhance risk absorption and expand resource mobilisation. Over time, they may progressively relieve pressure on sovereign financing, enabling health systems to access more diversified funding streams while reducing exposure to fiscal volatility. This, in turn, may lessen reliance on sovereign conditionalities and allow national governments greater implementation flexibility.

Operationalising this shift requires the development of a coherent investment architecture. One approach is the development of Population Equity Units (PEUs), which serve as the foundational analytical and financial entities within national systems. These units can be aggregated into stratified Demographic Asset Classes, reflecting variations in projected lifetime contribution, health system utilisation, and responsiveness to intervention. The introduction of such classifications enables a more granular understanding of where investments are likely to generate the greatest returns for national governments alongside the highest health-valued gains.

To support decision-making across this architecture, a Health Returns Value Index (HRVI) can be employed. The Index would provide a standardised metric for comparing Population Equity Units based on anticipated health outcomes relative to cost. This facilitates outcome-weighted health investment prioritisation, ensuring that limited resources are allocated in a manner consistent with maximising aggregate health systems performance. Importantly, such an Index would allow for dynamic recalibration over time, as demographic, epidemiological, and economic conditions evolve.

Within this framework, national health systems can be conceptualised as Health Equity Portfolios. These portfolios comprise a diversified set of Population Equity Units across multiple Demographic Asset Classes, each contributing differently to overall system yield. Standard portfolio management principles can then be applied, including allocation, rebalancing, and risk mitigation. High-performing segments—those demonstrating strong alignment between investment and realised outcomes—can be prioritised for sustained or increased capital allocation.

Conversely, Population Equity Units falling below defined marginal value thresholds may require structured reassessment. In such cases, mechanisms for managed transition, including consolidation or phased divestment, can be introduced to preserve portfolio efficiency. These processes should be governed by transparent criteria and embedded within broader national planning frameworks to ensure predictability and stability.

The potential integration of capital markets provides an opportunity to further enhance the flexibility of this model. Population Equity Units can be progressively bundled into tradable instruments, including outcome-linked bonds and equity participation vehicles. These instruments allow external sovereign and market investors to assume a share of the financial risk associated with health investments, while aligning returns directly with measurable outcomes. In doing so, they create a direct linkage between system performance and capital flows, reinforcing incentives for efficiency and innovation.

A complementary development is the introduction of rating systems for Demographic Asset Classes. Drawing on established methodologies from financial markets, population segments can be assigned standardised ratings based on projected return profiles and risk characteristics. AAA-rated population segments—those with high expected returns and low variability—can be prioritised for long-term investment, while sub-investment grade cohorts may be subject to targeted de-risking strategies, including controlled exposure limits, selective disengagement, or phased reallocation of resources. Rating migration over time provides an additional feedback mechanism, enabling continuous optimisation of the Health Equity Portfolio, including downgrade-triggered reallocation where required.

One of the strategic advantages of this approach for national governments is the reconceptualisation of equity. Rather than being treated as a purely distributive principle, equity can be operationalised as a function of participation and alignment with system performance requirements. Under this model, Population Equity Units hold differentiated positions within the national portfolio, reflecting their contribution to and benefit from collective investment. This ensures that resource allocation remains responsive to both system performance and evolving demographic realities.

Institutionally, the framework aligns with a broader functional redefinition of global health actors. Multilateral organisations, including normative bodies, can focus on establishing standards, developing metrics such as the HRVI, and convening stakeholders across sectors. Implementation and operational decision-making are devolved to national and regional entities, consistent with the principle of subsidiarity. This division of labour reduces duplication and enhances system coherence.

Financing flows, in turn, become more targeted and time-bound. Development assistance becomes progressively redundant, reducing exposure to sovereign conditionalities, and financing is repositioned as catalytic capital, supporting transitions toward domestically anchored and market-enabled systems. Global public goods—such as surveillance, research and development, and epidemic preparedness—remain appropriate areas for sustained collective investment, given their transnational nature and positive externalities. Nonetheless, they would need to demonstrate measurable impact on the Population Equity Units, and a positive return on investment.

The proposed model is not without complexity. The introduction of new instruments, metrics, and governance arrangements requires careful design and sequencing. Data systems must be strengthened to support accurate classification, valuation, and monitoring of Population Equity Units, with the resulting data architecture constituting a high-value analytical asset class in its own right, potentially suitable for managed service provision or structured private participation. Regulatory frameworks must evolve to accommodate novel financing mechanisms while safeguarding system integrity. Capacity building at national and subnational levels is essential to ensure effective portfolio management.

The risks of inaction, however, are far greater. Persisting with fragmented, input-driven, and fiscally unsustainable models will undermine both efficiency and impact. By contrast, a transition toward a maximally efficient, return-oriented framework offers the potential to sustain and enhance health outcomes despite resource constraints.

The convergence of fiscal pressure, institutional reform, and financial innovation creates a significant opportunity to re-engineer the global health architecture around principles of equity, efficiency, alignment, and sustainability. Through the structuring of Population Equity Units, the deployment of the Health Returns Value Index, and the gradual mobilisation of capital markets, it is possible to construct Health Equity Portfolios that are resilient, adaptive, and performance-oriented. Such an approach ensures that, even under conditions of constrained financing, health systems can continue to deliver measurable value at scale for national governments.

Health system sustainability is preserved through disciplined alignment of investment with demonstrable population value.

Campbell and Stanley explained replication rates in 1963

Over 60 years ago, Donald Campbell and Julian Stanley published their classic, slim volume Experimental and Quasi-Experimental Designs for Research. One of their earliest observations concerns the trade-off between internal and external validity. Specifically, the more precisely one can establish a causal relationship, the less one can say about its generality. In recent work, I show that simultaneously maximising internal and external validity is not merely a practical limitation to be mitigated, but a structural impossibility. The relationship is analogous to the Heisenberg uncertainty principle that shows one cannot simultaneously know both the position and momentum of a particle with arbitrary precision. In the context of the social and behavioural sciences, the more precisely one identifies a cause, the narrower the domain to which that knowledge applies.

I reviewed this problem in terms of the so-called “replication crisis”, the difficulty researchers have encountered in replicating published causal findings. Shortly after posting that paper, Nature published a series of articles on research credibility, including a large-scale investigation of replicability in the social and behavioural sciences. The empirical effort is extraordinary, involving hundreds of researchers and a substantial coordination infrastructure. The methods, results, and theoretical framing are all of considerable interest. However, the study has also generated headline figures that are readily misinterpreted—an outcome encouraged both by editorial framing and by the structure of the paper itself.

The central difficulty lies in two under-specified concepts that drive the research. The replication is of the “same question” and the “claim”. Whether a replication tests the “same question” is treated as a local, theory-laden judgement made by individual teams. Sameness is treated as constant at two levels simultaneously. First the multiple replications of a single study should be replicating the same thing, as if each attempt stood in an identical relationship to the original. And across all the original studies, the idea of sameness should stand in an identical relationship between a replication and its target regardless of which study is being replicated. If “same” does not mean the equivalent thing within and between replications, the target drifts meaninglessly

At the same time, replications are of “claims” which are scientific claims reduced to directional empirical statements, detached from the estimands, models, and analytic pipelines. That is, the claim is detached from the scientific meaning that gave it purchase in the original study. The same problem with “claims” arose in the team’s Nature paper on analytic robusteness. Abstracting scientific claims into more generic “claims” produces a mismatch between design and inference. Heterogeneous interpretations of what is actually being tested are collapsed into standardised statistical comparisons. Apparent agreement or disagreement may therefore reflect shifts in underlying targets rather than genuine replication or failure.

A related issue is that the study attempts to straddle internal and external validity without resolving their tension. It presents itself as assessing whether findings replicate, but in practice examines how results behave under modest variation in context, measurement, and implementation—something closer to robustness or transportability than strict replication. The use of multiple, non-equivalent metrics of “success” in the Nature article reinforces this ambiguity. Replication rates vary substantially depending on the criterion, yet a single headline figure is foregrounded: “Half of social-science studies fail replication test in years-long project“. The result is a study that is informative about the behaviour of findings (and researchers) under perturbation, but is easily—and predictably—read as making stronger claims about the reliability or truth of scientific results than its design can support.

Underlying both issues is a deeper disagreement about what replication is for. The paper’s opening paragraph explicitly reflects this tension. One reference is the National Academies of Sciences (NAS) report, which defines replication in procedural and statistical terms. Collect new data using similar methods and assess whether results are consistent, typically via effect sizes and uncertainty intervals. The other reference is a 2020 PLoS Biology article by Nosek and Errington (the two senior authors of this Nature paper), who argue that the NAS definition is not merely imprecise but conceptually mistaken. On the Nosek-Errington account, determining that a study is a replication is a theoretical commitment. Both confirming and disconfirming outcomes must be treated in advance as diagnostic of the original claim. The Nature paper adopts this language—replication teams were instructed to produce “good faith tests” of claims—but the article reports results entirely using metrics derived from the procedural-statistical tradition of NAS. This is not a superficial inconsistency. The two frameworks imply different standards of success, different interpretations of failure, and different meanings for any aggregated replication rate. The headline figures that have circulated are products of the latter framework; whether they would survive translation into the former is not addressed.

It is here that Campbell and Stanley’s observation, and its formalisation, becomes decisive. The procedural-statistical approach implicitly treats internal validity as primary and assumes that external validity can be inferred from it. That is, if results are consistent, the finding travels. The structural trade-off shows that this assumption cannot hold. The very steps taken to secure internal validity constrain the scope of generalisation. A high replication rate under this framework may therefore be simultaneously informative and misleading. It indicates that a result can be reproduced under sufficiently similar conditions, while obscuring how narrow those conditions may be. The Nosek-Errington framework recognises the need for theoretical commitment, but without a principled account of causal structure it cannot resolve the tension either. What the Nature paper ultimately demonstrates—perhaps inadvertently—is that replicability is not a property of findings alone. It is a property of the relationship between a finding and the conditions under which it is tested. This underscores a Cartwrightian notion of relationships tied to particular material configurations–nomological machines. Until that relationship is made explicit, headline replication rates will continue to invite overconfident conclusions in both directions and admonitions for better methods.

I did not have access to the published article which is behind the Springer-Nature paywall. Instead I relied on the publicly available preprint.