# Life Expectancy for Administrative Areas within Scotland, 2007-2009

2. Life expectancy at birth

2.1 The figures quoted in this publication are a three year average. They are produced by aggregating deaths and population data for the three year period. Three years of data are needed to provide large enough numbers to ensure that the figures published in this report are sufficiently robust.

2.2 The figures are all period life expectancies. Period life expectancies are calculated using age specific mortality rates for a given period. They do not make allowance for any actual or projected future changes in mortality after that period. This means that life expectancy at birth for a given time period and area is an estimate of the average number of years a new born baby would survive if he/she experienced the particular area’s age specific mortality rates for that time period throughout his/her life. The figure reflects mortality among those living in the area in each period, rather than mortality among those born in each area. Life expectancy at birth is not simply the number of years a baby born in the area during the three year period is expected to live (although the term ‘can expect to live’ is used throughout this publication for ease of reading), both because death rates are likely to change in the future and because many of the newborns may live elsewhere for at least some part of their lives.

2.3 Life expectancy at birth is also not a guide to the remaining expectation of life at any given age. It reflects the fact that survival from a particular age depends only on mortality rates beyond that age, whereas survival from birth is based on mortality rates at every age. Table 4 and Table 5 show life expectancy at an ‘exact age’. This is the average number of years those at this age would survive thereafter – if they experienced the particular area’s age specific mortality rates for that time period throughout the remainder of their life. These extracts from period life tables (found in Table 4 and Table 5) are constructed from the estimated population in 2007, 2008, 2009 and the total number of deaths registered in these years.

2.4 The column headed Ix shows the numbers who would survive to the exact age of x, out of 100,000 persons who, from birth were subject to the mortality rates of a given area in a given period. For example, in Glasgow City, 72.2 per cent of the male population and 83.6 per cent of the female population could be expected to survive to age 65 in 2007-2009. The column headed ex shows the expectation of life – the average number of years of life remaining to persons aged x. For instance, a male aged 65 in Glasgow City could be expected to live on average another 3.9 years, and a female aged 65 could be expected to live on average another 17.6 years.