Life Expectancy differs with the Environment - Essay Example

? Life Expectancy differs with the Environment (Country) Anita Dietmair Mrs. Jones IB Maths Standart July Life expectancy is a measure of population aging and is a reference to the average duration of time the members of a population can expect to live1. There is a difference between life expectancy and life span; life span is taken to be a theoretical biological reference to the highest number of years that a human can live under ideal conditions. Science has been able to come up with different life spans for different species; however it is unethical to do this for human beings as it requires environmental control to allow optimal conditions. The case of human beings determining a life span depends on the latest and reliable data on how long persons have actually lived. At the moment, it is documented that the lifespan of a human being is 120 years as determined by a French Woman, Jeanne Louise Calment, who passed on in 1997 aged 122 years2. Life expectancy is the median experience of a population. It is derived from existing mortality data gathered from a single year and evaluates what would happen to a hypothetical group of individuals if they lived experiencing the derived mortality rates indicative of the rates for the entire country as a whole during the year under consideration3. A low life expectancy is represented by lowest populations of aged people, lowest median and mean ages, and age/sex structures mostly reflective of pyramids4. There are many factors that define and determine the life expectancy of an individual. Consequently, there are various formulas that can be employed in obtaining the life expectancy of a given population. The first formula is the use of arithmetic mean to obtain the experience of individuals of a cohort. The use of arithmetic mean is attainable through the use of various data that include mortality rates, birth rates, and any other relevant data. Arithmetic mean, A has the formula: ; Where, A is the arithmentic mean, a­i…….an is the data contained in a given set, and n is the total number of individual counts in the data. This is one of the formulas used in finding the life expectancy of a population by taking the average of their expectancies based on specific data such as mortality or birth rate. In this respect, it means that individual life expectancies should be obtained in order to obtain their mean or average. Life expectancy of an individual can be established at birth when the age is 0 and assuming that the person is going to live for a given numer of years, ?. The life expectancy of an individual who will leave for ? years depend on the life probability at time t for the individual surviving from the 0 age to age ? (the highest age attained). Therefore, life expectancy at birth is a function of the age at that time and the highest age likely to be attained, which is illustrated as ; where L­e is the life expectancy at a particular age, x, and it is a function of O age and time, t. Based on the fact that life expectancy of an individual is a function of current age and the time he/she is likely to leave, the formula for life expectancy of an individual is as follows; In the above function, is the lifetable probability that the individual in question at time t will survive from birth to age a, and attain the highest possible age, ?. This is the formula for calculating the life expectancy of an individual at birth to a given age and possible the highest attained age. As will become apparent at the end of this study, life expectancy differs across different countries. At the same time, there is a clear difference between life expectancy levels of both males and females5. The differences in these two instances are caused by the same factors. The most significant factors are herewith discussed6. One of the most cited factors are differences in socioeconomic status. Most countries and individuals in these countries are at different economic stages. Some are more economically disadvantaged than others. It has been found that individuals or countries that have historically been economically disadvantaged, exhibited by such factors as unequal access to educational and occupational opportunity have lower life expectancies7. This is because these disadvantages often mean that these individuals cannot access important opportunities, such as employer-based health insurance and thus high mortality rates. Lastly, economically challenged countries or individuals have high prevalence of diseases a factor which increases mortality rates reducing life expectancy. In most studies, it has also become quite apparent that there is a clear variation in life expectancy arising from gender differences. As will be seen in subsequent representations, at every age, females have a higher life expectancy level than males. There has been a host of explanations seeking to describe this difference, ranging from scientific thoughts to creative ones8. The most reliable of these explanations and one that has its roots in scientific findings categorizes reasons into two, biological and social/behavioral explanations. The biological explanation is founded on the premise that females have a physiological advantage that translates to higher longevity. On the other hand, socio-behavioral explanations look at life-style choices, socialization, risk-taking, stress, and occupational hazards. Each of these explanations has evidence supporting their positions. An example of supporting evidence is the sex ratio. In regard to conception, there are 120 males conceived in every a 100 females, however, at the time of birth the numbers have dropped such that there are 105 males for every 100 females. In assuming that there are no social or behavioral factors affecting the prenatal stage then it is sound to conclude that male fetuses are less viable to female fetuses9. Another explanation is physiological, relating to heart diseases. Physiological studies indicate that before menopause, women are less likely to suffer from heart diseases that men, however, after menopause women’s rates almost equals that of men. The main explanation is that estrogen, a hormone produced in abundance during child bearing ages, helps protect women against heart diseases10. Apparently, the main differences in life expectancy are not wholly explained by the biological and physiological arguments.A part of the explanations allude to behavioral explanations which indicate that about 50% of the sex differential in mortality is explained by risk-taking and other unhealthy behaviors such as excessive drinking. Generally, men are considered to be more risk taking, and are prone to unhealthy behaviors such as smoking, fast driving, and infrequent visits to see a physician and are less likely to seek the help of support networks which increases stress levels11. It is clear that life expectancy is subject to variations in age, race, gender and economic situation. There are other multiple factors that determine how long individuals are likely to live. These variations are often unique to situations largely determined by either socioeconomic or genetic differences. Irrespective of the factors it is clear that life expectancies can be increased through access to more education, greater adaptation of technology, and higher incomes. Additionally, regular exercising, increased mental activity, stress management, controlling caloric intake, proper nutrition and regular visits to a physician would have a positive effect on life expectancy. In the wider picture, life expectancy can be increased through increased investment in scientific, medical, and pharmacological researches. Mathematically, it has been a challenge for most statisticians and mathematicians to develop models that directly determine life expectancy levels given the variability of the aforementioned levels. In the attempts made, life expectancy, also refered to as the mean residual life function, has been considered a fundamental model in characterizing distribution of residual life. One of the recognized model was developed by Oakes and Dasu (1990), the proportion mean residual life model, it is a regression model determining the link between life expectancy and asosicated variables12. The model of the proportion mean residual life was derived from the mean residual residual life function, which states that; the residual at a give time t, is defined as: Where, r(t) gives the expected remaining lifetime for an individual who has not have the opportunity of experiencing an event of interest at time t. Under the proportion mean residual life model, each variable is assumed to bear significant impact on life expectancy. However, correlation studies which are completed based on actual data help determine the degree of significance for each of the variables. In doing this, there has been general agreement that socioeconomic factors are the most significant determinants of life expectancy. This follows from the link that lower mortality and morbidity is always associated with positive socioeconomic status a correlation which has come to be refered to as “the gradient.” These factors will become clearer as the study progresses. This is because in the subsequent sections this study looks at specific cases of life expectancy in three different regions, Asia, Europe and Africa. In Asia, this study will focus on Japan, in Europe the study looks at United Kingdom (UK), and in Africa the study looks at South Africa. For clear analysis, mathematical formulas, tables and graphs will be incorporated while looking at each of the enumerated countries. Europe-United Kingdom United Kingdom is a sovereign state and is ranked among developed countries of the world. Its GDP is currently ranked sixth globally and is presently the eighth largest economy. Over the years, United Kingdom’s life expectancy levels have increased owing to a number of factors. The most notable of these factors is investment in the medical field dating back to the 17th and 18th century a time when Britain’s industrialization picked up13. Presently, Britain has suffered from an alarming mortality rate resulting from illnesses that other countries with significantly lower investments or at least the same investments in the medical fields have been able to manage. Over the years, the gap has widened further and experts warn that unless significant steps are taken the situation is likely to move from bad to worse. However, it has not always been grim for UK as over the years positive changes in life expectancy levels have been noted. For instance, from 1990 to 2010, a two decade period, life expectancy increased by an average 4.2 years. This increase left the life expectancy level in the UK at 79.9 years; this has further increased to the present average of 80.75 years14. Under normal circumstances, this would be considered a significant increment, however, UK officials and statisticians have pointed to a worrying decline. The main reason is because the relative life expectancy age is weighed against the levels in nations with similar medical infrastructures and levels of healthcare. These worries are founded by a look at the league table of nineteen countries indicating annual years of life lost (YLL) in every 100,000 people within a population. As per the table, UK was ranked tenth in 1990, presently the country has dropped to fourteenth position with only five countries being worse off. In regard to the number of deaths registered as per 100,000 members of the population the UK’s position has further dropped from the 12th position held in 1990 to position 14 in 201015. These are general figures pointing to the overall changes in life expectancy for individuals living in United Kingdom. However, a clearer picture is seen by examining a graph showing the general increase in the average years since 1980. The graph shows the general growth in life expectancy over the three decades (1980-2010). For ease of comparing the data, the change in life expectancy levels has been plotted for both males and females. Life expectancy at birth 1980-2010 As per the table, it is clear that life expectancy levels in the UK have consistently increased over the years to attain the highest level in 2010. The overall increase has been experienced in both females and males. From the graph, a baby boy would be expected to live 78.1 years while a girl would live for a few more years, 82.1 years. Another clear observation is that females just as highlighted by the preceding literature will be expected to live longer than males. However, a clear look demonstrates that the difference has been narrowing. This is in line with researchers’ observations that in two to three decades life expectancy among female and males will be the same. Even though there has been a general increase in life expectancy across both genders over the three decades it should be noted that the gap has narrowed from 6 years to 4.2 in 2010. Looking at 1980, 26 percent of males born would be expected to live for 65 years; this has since changed to 15 percent as per the 2010 rate. Similar figures for females have also declined from 16 percent in 1980 to 10 percent in 2010. Life expectancy for people aged 65, which represents the number of years an individual is expected to live after attaining 65 years in 2008-10, is higher for females than males. Based on the 2010 rates, a male at age 65 is expected to live for a further 17.8 years, a female aged 65 would be expected to live for a further 20.4 years. The difference between the two genders upon attaining the age of 65 in UK has gone down from four years in 1980 to 2.6 years in 2010. However, for objectivity, it should be noted that United Kingdom is made up of four regions, England, Wales, Scotland and Northern Ireland. Each of these regions posts a different life expectancy levels. The overall figures represented under UK are often an average of the four regions and the present study has chosen to focus on the overall (UK figures). Asia-Japan Japan is a country in East Asia and is the world’s third largest economy in terms of nominal GDP but overall fourth based on economy size. The country has a population of 127.8 million people based on World Bank’s 2011 estimates. In terms of life expectancy, Japan is referred to as the model nation as it has the highest life expectancy levels in the world irrespective of its huge population. As per the World Health Organization data, Japan held the top spot in 2011 in terms of average life expectancy for both females and males16. Generally, Japan being in the first spot is no surprise given that it has occupied the spot for the past two decades. However, there is a general observation that the pace at which the life expectancy level of other countries has been increasing Japan will soon surrender its position. This fact indicates that growth in Japan’s level of life expectancy is not as sharp as other countries which are bound to catch up. As per the 2011 data, Japan’s women were expected to live 86 years while their male counterparts were expected to live for 79 years17. Historically, Japanese life expectancy has not been as high, past data shows that there has been a 30 year increase in life expectancy levels since 194718. This is perhaps the sharpest increase across all countries and points to great positivity in terms of health investment. A clearer picture of Japan’s growth in life expectancy is seen when data starting 2000-2010 is plotted. Notably, the data is not differentiated between males and females but is representative of the overall increase in general life expectancy levels. Japan’s life expectancy at birth Country 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Japan 80.7 80.8 80.91 80.93 81.04 81.15 81.25 82.02 82.07 82.12 82.17 82.25 83.91 From the graph, it is clear that Japan’s level of life expectancy has been in ascendance since 2000. At an initial 80.7 years in 2000, individuals in Japan are now expected to live for 84 years (by 2012)19. The data is not indicative of the actual levels (for both sexes) especially given the fact that the male life expectancy levels are lower to those of females. However, at this point, the interest is on achieving a holistic figure of the general movement of average growth in life expectancy levels. Focusing on the graph, one notices that not only has there been a gradual increase but at times the life expectation at birth has spiked. An example of this is in 2006 when the rate increased by 0.8 years compared to previous growth increase of about 0.2 years annually. The most significant change was noted between 2011 and 2012 when the rate shot up by 1.8 years. Though these isolated movements point to incredible investments in the underlying factors affecting life expectancy it is safe to note that Japan’s increasing life expectancy level has been gradual pointing to consistency. Even though the graph indicates increasing life expectancy levels over the past decade it s noted that individual life expectancy levels for both sexes have started to decrease. For instance, Japanese female’s life expectancy at birth decreased from 86.30 in 2010 to 85.90 in 2011, similarly, males life expectancy dropped from 79.55 in 2010 to 79.44 in 2011. Though the drop is not significant it is feared that incrementally the drops may represent a reversal of the otherwise incredible increase over the years. The other factor worth noting is that over the decade, Japanese rate of increase in life expectancy has slowed down to about 0.2 years annually. This has been slower as compared to rates recorded in 1950-2000 which represented an annual growth of close to 0.4 annually. This represents a worrying trend for the Japanese as other countries are now recording higher annual growth figures and their model status might soon be overtaken by other countries improving at a greater pace. All the same, this worrying trend should not take away the present status of Japan as the world’s leader in life expectancy levels at birth. As would be gathered from the literature review done at the start of this study, it calls for extensive investment for a country to improve its life expectancy levels. Most of these investments must be geared to reducing mortality rates which erode the average level of life expectancy. Africa-South Africa South Africa is the southernmost country in Africa appearing at the tip of Africa. The country has a population of 50.59 million people as per World Bank 2011 approximations. South Africa though one of the best economically performing countries in Africa still suffers from a host of socioeconomic countries in Africa. Generally, a large number of African countries lag behind economically a factor that has had a major effect on health investment. South Africa is no different as economic struggles have hampered adequate investment in the health sector a fact that is so clear by a look at the country’s life expectancy levels. As at 2011, the life expectancy at birth for females was 53.21. 20This has been the highest level in the past decade. However, looking back, the country has achieved higher life expectancy levels for females; the highest ever was 63.35 achieved in 199021. 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 57.35 56.07 54.90 53.89 53.07 52.50 52.18 52.09 52.18 52.42 52.78 53.21 Presenting the above information in a line graph, the following is the results and depiction on how the life expectancy of women in South Africa has behaved between the period of 2005 and 2011. The graph shows a steady decline of life expectancy between 2000 and 2006 after which it started to increase towards 2012. It is not very different for men, in 2011; the life expectancy for South African males was 52.05. The highest level was 57.93 recorded in 1990 with the least that has ever been reported being 47.33 in 196022. The following table shows the difference in life expectancy levels for males in 2000-2011. 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 52.33 51.5 50.79 50.23 49.86 49.69 49.74 49.97 50.35 50.84 51.42 52.05 The above information can also be represented in the following graph for better picture in respect to changes in the life expectancy: From the above graph, it is clear that the life expectancy of men in South Africa has experienced a u-shape curve beween 2000 and 2011. There was a sharp decline in 2005 as depicted by the above graph. There is a need to understand the reasons explaining such a sharp decline, which was then followed by a steady increase in the life expectancy. In comparing the males and females in South Africa, the following is a combined table and graph showing how their life expectancies changed over a duration of 12 years from 2000 to 2011. Year 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Female 57.35 56.07 54.9 53.89 53.07 52.5 52.18 52.09 52.18 52.42 52.78 53.21 Male 52.33 51.5 50.79 50.23 49.86 49.69 49.74 49.97 50.35 50.84 51.42 52.05 This is presented in the following combined line graph One of the factors to note at this stage is that the life expectancy level in South Africa has been greatly weighed by the prevalence rates of HIV AIDS. As at 2011, 5.26 million South Africans were living with HIV. This number means that almost one in every ten South Africans is HIV positive. This high prevalence rate has meant that the life expectancy of the South Africans would continue to suffer until HIV AIDS is adequately dealt with. Failure will mean that the country’s life expectancy levels at birth will continually be lower to those of developed countries especially those discussed in this study. Overall table indicating South Africa’s life expectancy level at birth 2002-2010 Looking at the graph, one sees an inconsistent level of life expectancy. This inconsistency is not unique to this period, but is the case throughout South Africa’s history. However, with time a more consistent growth is expected if the growth seen from January 2006 is maintained. Notably, from 2006 there has been significant consistency (increasing life expectancy levels). Comparison Looking at the representations made in the analysis part of this study it is clear that the life expectancy level for Japan is the highest; this is followed by UK and South Africa respectively. In terms of range, Japan’s and UK’s life expectancy level at birth is comparable as there is only a slight difference, the average age in UK is 80.75 while in Japan the average is 82.5923. In a large way, this difference is reflective of respective policies and investments in eradicating health factors that often affect life expectancy. Similarly, this difference is indicative of the economic difference between the two economies. Looking at the literature reviewed at the start of the study, it is possible to see the positive correlation between economic well being and the life expectancy level of a country. This is particularly relevant in the case of Japan and UK. The following are date sets of Japan and UK in terms of how the GDP and disease prevalence (particularly AIDS) affect the life expectancy. In the study, it is important to develop a model, which need to be analyzed through Excel function in order to complete the model. The model use in this study for Japan and UK is illustrated below. Life expancy is affected by GDP, wage and the AIDS prevelance amongst other factors in a country, which is represented mathematically as; Life Expectancy (LE) = f (GDP, wage rate, AIDS prevalence) Taking Y for life expectancy, X1 for GDP, X2 for wage rate, and X3 for AIDS Prevalance; the model is expressed as; , Where, , ,, and are coefficients of the independent variables affecting the independent variable. A positive coefficient would indicate a positive correlation whereas a negative coefficient wold indicate a negative correlation between the independent and dependent variables. Notably, the strength of the correlation is also illustrated through the use of the coefficients. A coefficient that is greater than 0.5 shows that the relationship is very strong whereas a coefficient is less than 0.5 shows that the relationship between the independent and dependent variables is weak. Data was obtained from Worldbank databased and is represented in the following tables for Japan and UK. At the same time, the average life expectancy level of South Africans, 52.61 is also indicative of the socioeconomic challenges prevalent in the country. The above three countries in this study are compared and the results is displayed in the following table and graph. Overall Ranking Looking at the above graph it is possible to see the obvious high level of Japan’s level of life expectancy. United Kingdom is a distant nineteenth. Given that South Africa (not in this chart) has an average of 52.61 then it is safe to argue that it has one of the lowest life expectancy levels across the globe. Using Japan as the perfect model in improving life expectancy levels at birth one realizes that there is significant correlation between life expectancy and economic situation. Looking back at the Japanese situation, one can note that the level of life expectancy started to grow in the late 1950s and 60s a period that coincided with rapid economic growth24. As a result of increased development the government was able to find more resources to invest in public health and introduce universal health insurance which was put in place as early as 1961. At the same time, government provided free treatment for tuberculosis and introduced vaccinations which greatly reduced mortality rates25. At the same time, the government invested in pharmacology which helped produced drugs that tackled highly prevalent diseases such as stroke and blood pressure. This was jointly done with proper awareness on the importance of hygiene and nutrition. In total, these efforts helped cut mortality rates and at the same time provided for the increase of life expectancy levels. From this observation, it is plausible to conclude that the way to improving life expectancy level at birth is by bolstering the general economic situation. A sound economy generates enough resources to invest in public health and carry out necessary awareness. Bibliography Boseley, Sarah. Japan's life expectancy down to equality and public health measures. August 30, 2011. http://www.guardian.co.uk/world/2011/aug/30/japan-life-expectancy-factors (accessed July 20, 2013). Danninger, Stephan. 2012. Japan selected issues. Washington, D.C.: International Monetary Fund. http://www.imf.org/external/pubs/ft/scr/2012/cr12209.pdf. Index Mundi. Life expectancy at birth-South Africa. 2012. http://www.indexmundi.com/facts/south-africa/life-expectancy-at-birth (accessed July 20, 2013). Index Mundi. Life expectancy in Japan. 2012. http://www.indexmundi.com/g/g.aspx?v=30&c=ja&l=en (accessed July 20, 2013). Morgan, Leslie A., and Suzanne Kunkel. 2007. Aging, society and the life course. New York: Springer. Nair, Vijay, and Kjell A. Doksum. 2007. Advances in statistical modeling and inference: essays in honor of Kjell A. Doksum. Singapore: World Scientific. Office of National Statistics UK. 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