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22 June 2020 | Story Andre Damons | Photo Anja Aucamp
Herkulaas Combrink.

A lot can be said about forecasting and modelling, its accuracy, and how it works. Forecasting and modelling provide any decision-maker with plausible predictions or outcomes to give some kind of estimated consequence. Without this field of science, planning would be difficult, as one would simply make decisions without knowing what might potentially happen to a specific cohort, market, or product. Forecasting as a concept can be seen as a set of mathematical, statistical and/or computational tools applied to a set of assumptions about something.

This is according to Herkulaas Combrink of the Centre for Teaching and Learning at the University of the Free State (UFS) and PhD candidate in Computer Science at the University of Pretoria (UP), following the South African government’s modelling of how many people would contract COVID-19 and die, which has come under fire in recent times – with one expert saying it was “flawed and illogical and made wild assumptions”. 

Combrink is of the opinion that South Africa – by using the MASHA Consortium – is using the best minds that the country has to offer. The fact that the leadership took a pragmatic stance and reached out to the scientific community has mitigated a medical disaster in a healthcare system that was not ready a few months ago.

“The government is looking at as many models as they can, but is working very closely with MASHA and the CSIR” says Combrink, who has been involved in clinical surveillance, and also forms part of the modelling team during his secondment to the Free State Department of Health. 

Prof Shabhir Madhi, the former head of the SA National Institute for Communicable Diseases (NICD), recently said that the initial modelling and fatality estimates were “back-of-envelope calculations”.

According to a news report, the government’s initial model also predicted that 600 COVID-19 patients would need treatment in intensive care units (ICU) in SA by April 1. But by April 18, the last publicly released figures showed that there were 32 COVID-19 patients in ICU.

Tried-and-tested models
The models currently used are tried-and-tested epidemiological models, mathematical models, and economic forecasting models that have been used in the past. It has now been calibrated to the specifications that we know of this disease, which come from publications. The reason why you would use more than one model is to compare models retrospectively, so that you can see what is going on.

“The government immediately reached out to the best minds in the country, and with the aid of the consortium, took a stance to throw scenarios at the different models and stress test them so that they could know that they are using the best possible models to assist in resource management and decision-making. If government responded in a different way and didn’t reach out, we might not have had a lockdown and subsequently would probably have been in a different position where the country wouldn’t be ready.” 

“We can say with a high degree of confidence that the lockdown really helps to ease and flatten the curve in the country. In light of flattening the curve, the right decisions have been made,” says Combrink.

COVID-19 still new
Unfortunately, says Combrink, during the COVID-19 pandemic, there was not enough information related to the disease assumptions and it lacked the rigour and perfection associated with the already existing prediction models. Although it may feel like a lifetime, the first COVID-19 case was only reported in December 2019. Add to this that not all the parameters related to the disease were known in January, it was challenging to determine all the ‘ins and outs’ of this disease. 

“Luckily, the mathematics and statistics of an outbreak have been extensively studied, and as a result, we only needed to use the correct parameters to estimate the spread of the disease in some of the outbreak models. The Minister of Health, Dr Zweli Mkhize, and the national modellers led by Dr Harry Moultrie, were transparent with not only their projections, but also how they derived their conclusions and what parameters they used,” says Combrink.

The most important thing in modelling is to calibrate according to what is known about the disease and people, explains Combrink. “It is impossible to predict people and a disease100% accurately, because you don’t always know how a virus will react to every single person’s body and you can’t predict human behaviour.” 

“So, there is a certain degree of error and a certain degree of confidence that lies within each model, and that is why you evaluate these models on a regular basis. And this is important. You will never be able to say this is the exact number. Just like the weather. If the weather patterns were predicted to be 12 degrees tomorrow, and it turns out to be 16 degrees, you at least packed a jersey. You knew it was going to be cold. The chances that the weather predicts that it will be 12 and it turns out to be 57 degrees, is virtually zero. It gives you more or less an indication what to prepare for

Models are useful, but can also be wrong
Combrink says if you want to apply any model, you need to understand the assumptions and the limitations of the models. Given a certain set of criteria – what are the assumptions you are making and what are the expected outcomes – you can only act according to that. He says, as time goes by, we can now see that there are some models that yield much better results because we can now compare what was predicted two months ago and what is actually happening. 
 “Some models are useful. We can get a better understanding of the pandemic’s possible trajectories or gain an understanding of the impact that different interventions have made. Models are used for decision-making. These decision-making strategies can save lives. That is the purpose of models and modelling during these times.”

Combrink uses the weather forecast to explain how modelling works and that models can be wrong. “Yes, models are wrong all the time. Take the concept of weather as an example. How many times has the weather forecast predicted that there is an 80% chance of rain, and then it doesn’t rain? Models can give you a certain degree of confidence in an outcome related to a specific event or scenario, so that you, with some degree of confidence, can go forth and plan accordingly.” 

“However, models can’t tell you what exactly will happen tomorrow, or the day after. It is not a crystal ball, and it is not a mirror into the future, but it can give you an indication of what is likely possible related to a specific scenario if you used the right variables. Let us consider that there is an 80% chance of rain in the weather forecast; will you a) go to work without an umbrella or b) with an umbrella? If it doesn’t rain, you are at least prepared for the rain because you took your umbrella. If you didn’t take the umbrella and it does rain, you may run into trouble because you did not appreciate the warning of the weather forecast. I think it is this concept that makes modelling so powerful. You can use it as a tool to prepare for things, in the event that it does happen, with a certain degree of confidence. Just like the previous example, there is also a 20% chance that it might not rain, but wouldn’t you want to be prepared?” explains Combrink. 
 
Models are tools that can be used to base decisions on
No one truly knows how the pandemic will play out, and according to Combrink, it can be said with a high degree of confidence that if nothing is done about the pandemic, we know how it would turn out from a healthcare perspective. 
“If you look at some of the global projections they gave months ago (in January and February) and compare it to what they said for March and April, you can see that they predicted, with a fairly good degree of confidence, what actually happened in certain countries. We have a good idea in terms of numbers and how it will play out, but what we will never know is what the impact will be on the socio-economic status of a person, the economy, and the impact on other diseases.”

“We do not know what is going to happen when it comes to mental health and COVID-19, for example. This is why modelling is a multidimensional approach, requiring inputs from various fields. Models can help us in the same way the weather forecast does. It is a tool that we can use to base certain decisions on, to be more prepared, because without it we won’t know to pack an ‘umbrella’ if it is predicted to rain or pack a ‘jersey’ if it is projected to cool down.”

News Archive

Media: Sunday Times
2006-05-20

Sunday Times, 4 June 2006

True leadership may mean admitting disunity
 

In this edited extract from the inaugural King Moshoeshoe Memorial Lecture at the University of the Free State, Professor Njabulo S Ndebele explores the leadership challenges facing South Africa

RECENT events have created a sense that we are undergoing a serious crisis of leadership in our new democracy. An increasing number of highly intelligent, sensitive and committed South Africans, across class, racial and cultural spectrums, confess to feeling uncertain and vulnerable as never before since 1994.

When indomitable optimists confess to having a sense of things unhinging, the misery of anxiety spreads. We have the sense that events are spiralling out of control and that no one among the leadership of the country seems to have a definitive handle on things.

There can be nothing more debilitating than a generalised and undefined sense of anxiety in the body politic. It breeds conspiracies and fear.

There is an impression that a very complex society has developed, in the last few years, a rather simple, centralised governance mechanism in the hope that delivery can be better and more quickly driven. The complexity of governance then gets located within a single structure of authority rather than in the devolved structures envisaged in the Constitution, which should interact with one another continuously, and in response to their specific settings, to achieve defined goals. Collapse in a single structure of authority, because there is no robust backup, can be catastrophic.

The autonomy of devolved structures presents itself as an impediment only when visionary cohesion collapses. Where such cohesion is strong, the impediment is only illusory, particularly when it encourages healthy competition, for example, among the provinces, or where a province develops a character that is not necessarily autonomous politically but rather distinctive and a special source of regional pride. Such competition brings vibrancy to the country. It does not necessarily challenge the centre.

Devolved autonomy is vital in the interests of sustainable governance. The failure of various structures to actualise their constitutionally defined roles should not be attributed to the failure of the prescribed governance mechanism. It is too early to say that what we have has not worked. The only viable corrective will be in our ability to be robust in identifying the problems and dealing with them concertedly.

We have never had social cohesion in South Africa — certainly not since the Natives’ Land Act of 1913. What we definitely have had over the decades is a mobilising vision. Could it be that the mobilising vision, mistaken for social cohesion, is cracking under the weight of the reality and extent of social reconstruction, and that the legitimate framework for debating these problems is collapsing? If that is so, are we witnessing a cumulative failure of leadership?

I am making a descriptive rather than an evaluative inquiry. I do not believe that there is any single entity to be blamed. It is simply that we may be a country in search of another line of approach. What will it be?

I would like to suggest two avenues of approach — an inclusive model and a counter-intuitive model of leadership.

In an inclusive approach, leadership is exercised not only by those who have been put in some position of power to steer an organisation or institution. Leadership is what all of us do when we express, sincerely, our deepest feelings and thoughts; when we do our work, whatever it is, with passion and integrity.

Counter-intuitive leadership lies in the ability of leaders to read a problematic situation, assess probable outcomes and then recognise that those outcomes will only compound the problem. Genuine leadership, in this sense, requires going against probability in seeking unexpected outcomes. That’s what happened when we avoided a civil war and ended up with an “unexpected” democracy.

Right now, we may very well hear desperate calls for unity, when the counter-intuitive imperative would be to acknowledge disunity. A declaration of unity where it manifestly does not appear to exist will fail to reassure.

Many within the “broad alliance” might have the view that the mobilising vision of old may have transformed into a strategy of executive steering with a disposition towards an expectation of compliance. No matter how compelling the reasons for that tendency, it may be seen as part of a cumulative process in which popular notions of democratic governance are apparently undermined and devalued; and where public uncertainty in the midst of seeming crisis induces fear which could freeze public thinking at a time when more voices ought to be heard.

Could it be that part of the problem is that we are unable to deal with the notion of opposition? We are horrified that any of us could be seen to have become “the opposition”. The word has been demonised. In reality, it is time we began to anticipate the arrival of a moment when there is no longer a single, overwhelmingly dominant political force as is currently the case. Such is the course of history. The measure of the maturity of the current political environment will be in how it can create conditions that anticipate that moment rather than seek to prevent it. We see here once more the essential creativity of the counter-intuitive imperative.

This is the formidable challenge of a popular post-apartheid political movement. Can it conceptually anticipate a future when it is no longer overwhelmingly in control, in the form in which it is currently, and resist, counter-intuitively, the temptation to prevent such an eventuality? Successfully resisting such an option would enable its current vision and its ultimate legacy to our country to manifest in different articulations, which then contend for social influence. In this way, the vision never really dies; it simply evolves into higher, more complex forms of itself. Consider the metaphor of flying ants replicating the ant community by establishing new ones.

We may certainly experience the meaning of comradeship differently, where we will now have “comrades on the other side”.

Any political movement that imagines itself as a perpetual entity should look at the compelling evidence of history. Few movements have survived those defining moments when they should have been more elastic, and that because they were not, did not live to see the next day.

I believe we may have reached a moment not fundamentally different from the sobering, yet uplifting and vision-making, nation-building realities that led to Kempton Park in the early ’90s. The difference between then and now is that the black majority is not facing white compatriots across the negotiating table. Rather, it is facing itself: perhaps really for the first time since 1994. Could we apply to ourselves the same degree of inventiveness and rigorous negotiation we displayed leading up to the adoption or our Constitution?

This is not a time for repeating old platitudes. It is the time, once more, for vision.

In the total scheme of things, the outcome could be as disastrous as it could be formative and uplifting, setting in place the conditions for a true renaissance that could be sustained for generations to come.

Ndebele is Vice-Chancellor of the University of Cape Town and author of the novel The Cry of Winnie Mandela

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