Forever Growing:

The final component in which math contributes significantly to health and medicine concerns life expectancy. Life expectancy summarises the remaining years of life that a person is expected to live. This varies (sometimes drastically) across the world and even among different ethnic and gender groups within the same country and is due to the numerous factors that can positively or negatively affect the life people lead.

Some factors that influence life expectancy include:

• Poverty/Gross Domestic Product (GDP),
• Sanitation,
• Diet,
• Climate,
• Exercise,
• Nation expenditure for health care,
• Access to health care,
• Urbanisation, and
• Disease outbreak

There are numerous sources for exploring life expectancy. Some notable ones include Australian Bureau of Statistics (ABS) and the Central Intelligence Agency (CIA) World Factbook.

Life expectancy is calculated through data acquired in a population census. A census is the process by which information about a country’s population is formally acquired and recorded. It originated in 1662 when John Graunt used morality rolls to conduct the first statistically based population estimation, in this case the population of London.

In Australia, the census is taken every five years by the ABS. From this information, it becomes evident that in Australia the general trend is a consistent increase in life expectancy. 

Internationally, more economically developed nations generally have higher life expectancy rates. For the most part, the countries with the top twenty highest life expectancies all have a system of universal health care. However, in general, life expectancy has increased considerably since the early 20th century.

One of the most important factors responsible for the international increase in life expectancy comes from advances in public health. These include the discovery of penicillin, the invention of vaccinations such as the polio vaccine, and advances in medical detection and treatment technology.

However, when looking at life expectancy data it is important to recognise that there can be inherent biases or errors within the census system. For example when analysing the census data on Indigenous Australians, it is important to note that they were not officially included until 1971. Also, we need to consider that census questions are often structurally bias, usually due to the constraints that the census’ format places on the ABS.

While in western countries life expectancy has generally increased since the early 20th century, it is important to note that some analysts believe that in some countries this trend may reverse itself. This is believed to be base of rising levels of obesity and the health risks that accompany them.

 

Exercise 1

• Using an online life expectancy calculator (such as mylongevity), obtain an estimate on your own life expectancy. As a class, collate the results and graph using spreadsheet software. Is there much variation in the life expectancy amongst your class? These kinds of calculators shouldn't be taken as absolute, however they can give an indication on how certain life factors can directly impact your 'expected' length of life. Following this, use hypothetical information in the calculator to observe the effect of different factors on a person's life expectancy. 

• Using the following information, plot the life expectancy for men against the life expectancy for women across different countries using Microsoft Excel ©. Establish a line of best fit for the data and comment on the correlation between the two sets of data. 

• If you were to add the following data to your scatter plot, how would this affect the correlation and line of best fit? What reasons can you provide that might explain the differences in life expectancy between countries?

*Cover photo taken from http://www.washingtonpediatric.com/staff.php