Measuring food and health practice questions.

A student maps hospital admissions for the regions of France by shading each region according to the total number of admissions recorded there in one year. Why is the resulting choropleth map misleading?

• Choropleth maps are restricted to a maximum of four data classes
• Populous regions shade darker simply because more people live there
• Absolute totals may not be mapped at the regional scale under any circumstances
• Choropleth shading has to use a diverging colour scheme to be valid

Answer: Populous regions shade darker simply because more people live there

Choropleth shading is read as intensity per unit area, so a map of raw totals mostly shows where the people live rather than where health need is greatest. Admissions per 1 000 residents restore the comparison, which is why health is compared through rates rather than counts.

A country reports adequate average calorie availability per person, yet a fifth of its children are stunted. Which conclusion follows?

• Availability of food does not guarantee access to it or dietary quality
• The calorie estimate must have been calculated incorrectly
• Stunting is unrelated to nutrition in any circumstances
• The country must be exporting all of its food production

Answer: Availability of food does not guarantee access to it or dietary quality

Food security has four pillars - availability, access, utilisation and stability - and a national average speaks only to the first. Unequal distribution, poverty, poor sanitation and a diet short of protein and micronutrients all produce stunting where calories are sufficient.

Two countries have the same life expectancy at birth, but one has a much lower health-adjusted life expectancy. What does this tell you?

• Its people spend more of their lives in poor health or with disability
• Its life expectancy figure has been overestimated
• It has a younger population structure than the other
• It has a higher infant mortality rate than the other

Answer: Its people spend more of their lives in poor health or with disability

Health-adjusted life expectancy discounts years lived with illness or disability, so the gap between it and life expectancy measures the burden of chronic ill health. Two populations can live equally long and experience those years very differently.

As a country develops, deaths from infectious disease fall while deaths from cardiovascular disease and cancer rise. Which model describes this shift?

• The epidemiological transition
• The demographic transition
• The nutrition transition
• The Butler tourist area life cycle

Answer: The epidemiological transition

The epidemiological transition tracks the changing causes of death as sanitation, nutrition and medicine improve and populations age. The nutrition transition is the related but distinct change in what people eat, and the demographic transition tracks births and deaths rather than causes.

In a nutrition survey of children under five, which measurement identifies acute (recent) undernutrition rather than long-term chronic undernutrition?

• Height-for-age more than two standard deviations below the reference median
• Weight-for-age more than two standard deviations below the reference median
• Weight-for-height more than two standard deviations below the reference median
• Head circumference more than two standard deviations below the reference median

Answer: Weight-for-height more than two standard deviations below the reference median

Weight is lost quickly relative to height, so wasting records a recent food shortage or illness; height-for-age (stunting) records cumulative deprivation over years and does not recover when feeding improves, while weight-for-age mixes the two and cannot separate them.

A briefing note states: 'India recorded far more undernourished people than Timor-Leste, so undernutrition is more severe in India.' Which single flaw does this reasoning contain?

• It compares absolute numbers of people instead of prevalence rates
• It uses undernourishment when stunting is the only valid measure
• It compares two countries whose data were collected in different years
• It assumes food supply data are gathered by household survey

Answer: It compares absolute numbers of people instead of prevalence rates

A country with a very large population can hold the largest number of undernourished people while having a lower share of its population affected, so severity comparisons need a rate; the size of the denominator is what the note has ignored.