Author: Laura Dewis

Poverty and Disease

Updated Wednesday, 14th July 2004
Course extract from Preparing For Development - Poverty and Disease

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An infant receives treatment

As well as low education levels, some of the other factors I have mentioned (lack of access to health facilities, overwork, etc.) are also linked to poverty. This, for many, is the main cause of ill-health and it is to the links between poverty and disease that I now turn.

In this section I am going to take a measurable definition of poverty based on income (but do note that poverty has several dimensions other than those directly related to material wealth). This is the poverty line which is set by the World Bank at an annual income per person of US$370. The percentage of people who fall below that line in a population is known as the headcount index, so the greater the headcount index, the greater the poverty in the population.

Headcount index (%)

Activity Nine

Examine the table, which shows the headcount index and under-five mortality rate for different regions of the developing world.
At first glance the table may look like a jumble of figures and make no sense. The easiest way to make sense of it and to pick out any trends is to display the data visually. To do this you need to complete this graph:


If you feel unsure about your graph-drawing abilities, I have plotted points for Mozambique, China and India to help you start. Examine, for example, the mark for China, which is bottom left in the graph. China has a headcount index of 18, so it is just before the line marking 20 as you read from left to right. On the other hand, China's under-five mortality rate is36, so it appears just below the '40' line as you read the graph from bottom to top.

Do not try to join up the points when you have completed the activity - it is not that sort of graph.

What general trend can you observe from your graph?

We'll look at an answer on the next page

An elderly lady in China Activity Nine: A sample answer

You were asked: What general trend can you observe from your graph?

The graph you have drawn is a scatter diagram, so-called because the points are scattered about. However, you can see a definite pattern or trend. In general, as the headcount index increases, so too does the under-five mortality rate for a country.
So you can conclude that there is a link or correlation between poverty (as measured by the headcount index) and child mortality. If the points were scattered about with no pattern, you would conclude there is no correlation. The graph shows a positive correlation; as one indicator increases so does the other. A pattern at right angles to the one you have drawn would show a negative correlation. It would mean that as one indicator increases, the other decreases. This would occur if you plotted an opposite indicator to under-five mortality rate, such as life expectancy, against headcount index.. So does the positive correlation between headcount index and under-five mortality rate show that poverty causes disease?

The answer, unfortunately, is not so simple, as we shall see on the next page.

Do telephones give you colon cancer? Activity Ten

Examine this graph.

phones and colon cancer

Is there a correlation between cancer of the colon and telephone ownership? If so, is it a positive or negative correlation? Do you think that telephone ownership causes cancer of the colon?

There is a positive correlation between owning a telephone and cancer of the colon. So does this mean that owning a telephone causes cancer of the colon?

Common sense tells us that this is ridiculous. Does having cancer of the colon cause people to go out and buy a telephone? This is slightly more plausible, but still very far-fetched.

Activity Eleven

Write down two or three factors that telephone ownership indicates which might link it to cancer of the colon.

We'll look at possible answers - and review the skills you've been using - on the next page.

Access to health facilities: A strong proxy indicator

Activity Eleven: Suggested Answers

You were asked: Write down two or three factors that telephone ownership indicates which might link it to cancer of the colon.

High telephone ownership in a country indicates a western lifestyle. We can call it a proxy for such a lifestyle. One feature of a western lifestyle is a highly refined, meat-based diet. It is probably this diet that is a direct cause of cancer of the colon. In other words, telephone ownership and cancer of the colon are both linked to the western lifestyle. This seems a more sensible way of explaining the correlation than trying to suggest that owning a telephone directly causes cancer of the colon?

Definition: Proxy
This is a relatively simple substitute for something that is too complex to measure in its entirety (e.g. lifestyle).The point of the telephone-cancer example is that statistical correlations by themselves prove nothing. We need other evidence to establish fully whether poverty causes disease, or whether it is the other way round. Are the two linked to a third factor? Perhaps the correlation is purely chance.

So where does this leave us with our poverty-disease correlation?

My own opinion is that poverty is a basic cause of disease. Malnutrition, lack of education, lack of clean water and lack of access to health facilities are all also positively correlated with disease incidence. It is because these indicators are themselves so strongly linked to poverty that many people call them proxy indicators.

Study skills review: reading numbers in tables and graphs

Numbers by themselves are meaningless. To turn them into useful information they have to be compared with other numbers, to make out patterns and to draw links between numbers that represent different things.

That is what you have been doing for most of this taster.
Sometimes the examination has been fairly superficial, as in the earlier section when you drew a link between education and disease by simply examining a few countries at the top and bottom of the adult illiteracy and under-five mortality ranges and concluding that if one is high, the other is likely to be high too.

Looking at high and low numbers in the columns of a table is a good start to reading them. It gives a feel for the data and suggests the patterns that probably exist. Something similar happens when you listen to a piece of music for the first time. You might know you like it, but you will have to listen to it several times before you discern properly its melody and words.But it is also important to note the numbers that don't easily fit into the broad pattern. We are dealing with the real world where nothing fits perfectly and these exceptions can often tell us a great deal.

In Activity nine you went beyond the superficial examination and, by drawing a graph, established in some detail the pattern that exists between poverty and disease. There are many kinds of graph and chart (the one you drew is called a scatter diagram) but they all share in common the aim of making obvious the patterns that exist in tables of numbers. Whenever you decide to draw a graph, ask yourself first whether or not it will help to illustrate the patterns. If not, don't bother.

Tables and graphs, in the end, are no more than models of reality, where the real world is represented in number form and re-jigged so that the numbers supply useful information that can further our understanding.

In section six, we'll consider ways that health standards can be improved.

About this sample

This course sample is adapted from Preparing For Development, part of the U213: International Development: Challenges for a world in transition and TU871: Development: Context and practice courses.


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