Subjective age

Subjective life expectancy and subjective age


LASA094

Contact: Dorly Deeg

Background
Whereas the societal consequences of increasing longevity are widely discussed, much less attention is paid to the individual experiences of prolonged ageing. More insight in individual perspectives may be obtained by studying how older people experience ageing. Questions are: how old do people feel, and how do they experience their remaining life expectancy? The former is commonly measured by the concept of subjective age, and the latter, by the concept of subjective life expectancy. Both concepts have been found to affect behaviour such as retirement from work, health habits, use of health care services, and well-being (Mirowsky, 1999; Scott-Sheldon et al., 2010; van Solinge en Henkens, 2009; Ziegelmann, Lippke en Schwarzer, 2006).

Measurement 1: LASA life-line
In the Longitudinal Aging Study Amsterdam main interview, both concepts subjective age and subjective life expectancy are combined in the ‘life-line’. This is a line of length 25 cm representing the life course from beginning to end (see figure 1), on which the respondent is asked to position himself or herself prompted by the question: ‘Can you please indicate with a cross where on your life-line you feel you are at the present moment?’

Beginning End


Figure 1. The LASA life-line as presented to the respondent. The cross represents a sample response (score calculated as 0.66).

During the data processing, the place of the cross is measured in centimetres and rescaled to a score between 0 and 1.

The life-line score can be interpreted as the self-perceived life stage. From the score, furthermore, the subjective age and the subjective life expectancy can be derived.

Subjective age
Age can be defined as the distance in years from birth. Likewise, subjective age can be defined as the experienced distance to birth. To calculate subjective age, it is assumed that the total life span is the sum of the chronological age and the remaining actuarial life expectancy from the chronological age. For example, for a man aged 61 in 1998, the remaining life expectancy was 18 years, and his total life span is calculated as:

           61+18=79 years.

The subjective age is then calculated by multiplying the life-line score with the estimated total life span. If the cross in the figure would be placed by the man of the example, his subjective age would be:

           79*0.66=52 years.

Subjective life expectancy
Remaining life expectancy can be defined as the distance in years to death. Likewise, subjective (remaining) life expectancy can be defined as the experienced distance to death. Two steps are taken to calculate subjective life expectancy. First, the chronological age is divided by the life-line score in order to obtain the subjective total life span. In the example, this is:

           61 / 0.66=93 years.

Second, the chronological age is subtracted from the total life span, which results in the subjective remaining life expectancy. In the example, this is:

           93 – 61 = 32 years.

Measurement 2: Subjective age and subjective life expectancy explicit questions
In 2008-09 (wave LASA-G), in the main interview prior to administering the ‘life-line’, explicit questions were asked about participants’ perceived age, desired remaining life years, expected remaining life years, and their preference for a longer or shorter life in the presence of health problems (Ziegelmann et al 2006).

Questionnaires
Lifeline: LASAD094 / LASAE094 / LASAF094 / LASAG094 / LASAH094 / LASAI094;
Subjective age / Life expectancy: LASAG094 / LASAH094 / LASAI094 (main interview, in Dutch)

Variable information
Life-line: LASAD094 / LASAE094 / LASAF094 / LASAG094 / LASAH094 / LASAI094;
Subjective age / Life expectancy: LASAG094 / LASAH094 / LASAI094
(pdf, in preparation)

Availability of information per wave1 

 

B

C

D

E


2B*

F

G

H



3B*

MB*

I*

Life-line

 

 

Ma

Ma

-

Ma

Ma

Ma

-

-

Ma
Subjective age / Life expectancy     - - - - Ma Ma - - Ma

1 More information about the LASA data collection waves is available on:
 http://www.lasa-vu.nl/data/lasa/sampleLASAdatacollection.html

* 2B=baseline second cohort;
  3B=baseline third cohort;
  MB=migrants: baseline first cohort (Under Construction);
  I=Under Construction

Ma=data collected in main interview

Previous use in LASA
The explicit question on subjective life expectancy proved to be associated with attitude towards euthanasia (Buiting et al 2012). The relations of the life-line score with chronological age and actuarial life expectancy are described by Thijsen and colleagues (2014).

  • Buiting HM, Deeg DJ, Knol DL, Ziegelmann JP, Pasman HR, Widdershoven GA, Onwuteaka-Philipsen BD. Older peoples' attitudes towards euthanasia and an end-of-life pill in The Netherlands: 2001-2009. J Med Ethics 2012; 38(5): 267-273.
  • Thijsen A, Wiegersma SB, Deeg DJH, Janssen F. Leeftijd is meer dan een getal: subjectieve levensverwachting onder Nederlandse ouderen [Age is more than a number: subjective life expectancy in Dutch older people]. CBS Bevolkingstrends, January 2014: 3-13.

References

  1. Mirowsky J. Subjective life expectancy in the US: Correspondence to actuarial estimates by age, sex and race. Social Science and Medicine 1999; 49(7): 967–979.
  2. Scott-Sheldon LAJ, Carey MP, Vanable PA, Senn TE. Subjective life expectancy and health behaviors among STD clinic patients. American Journal of Health Behaviour 2010; 34(3): 349–361.
  3. Van Solinge H, Henkens K. Living longer, working longer? The impact of subjective life expectancy on retirement intentions and behaviour. European Journal of Public Health 2009; 20(1): 47–51.
  4. Ziegelmann JP, Lippke S, Schwarzer R. Subjective residual life expectancy in health self-regulation. Journals of Gerontology 2006; 61B(4): P195–P201.

In LASAD094 at wave D a 'happiness-line' was added identical to the life-line. For the description of this subject see the documentation on Satisfaction with life and happiness.