Longitudinal study

A longitudinal survey is a correlational research study that involves repeated observations of the same variables over long periods of time, often many decades. It is often a type of observational study, although they can also be structured as longitudinal randomized experiments.[1] Longitudinal studies are often used in psychology, to study developmental trends across the life span, and in sociology, to study life events throughout lifetimes or generations. The reason for this is that unlike cross-sectional studies, in which different individuals with the same characteristics are compared,[2] longitudinal studies track the same people and so the differences observed in those people are less likely to be the result of cultural differences across generations. Longitudinal studies thus make observing changes more accurate and are applied in various other fields.

In medicine, the design is used to uncover predictors of certain diseases. In advertising, the design is used to identify the changes that advertising has produced in the attitudes and behaviors of those within the target audience who have seen the advertising campaign.

When longitudinal studies are observational, in the sense that they observe the state of the world without manipulating it, it has been argued that they may have less power to detect causal relationships than experiments. However, because of the repeated observation at the individual level, they have more power than cross-sectional observational studies, by virtue of being able to exclude time-invariant unobserved individual differences and also of observing the temporal order of events. Some of the disadvantages of longitudinal study include the fact that they take a lot of time and are very expensive. Therefore, they are not very convenient.[3]

Longitudinal studies allow social scientists to distinguish short from longterm phenomena, such as poverty. If the poverty rate is 10% at a point in time, this may mean that 10% of the population are always poor or that the whole population experiences poverty for 10% of the time. It is impossible to conclude which of these possibilities is the case by using one-off cross-sectional studies.

Types of longitudinal studies include panel studies and cohort studies. Cohort studies sample a cohort, defined as a group experiencing some event (typically birth) in a selected time period, performing a cross-section at intervals through time. Panel studies also use cross-sectional data and compare the same group of individuals at intervals through time, but the sample is not necessarily a cohort, as it can be a group of people that do not share a common event. Therefore, a cohort study can be considered a panel study, but a panel study is not always a cohort study.[4]

A retrospective study is a longitudinal study that looks back in time. For instance, a researcher may look up the medical records of previous years to look for a trend.

Examples

Study name Type Country or region Year started Participants Remarks
Alzheimer's Disease Neuroimaging Initiative Panel International 2004 n/a -
Australian Longitudinal Study on Women's Health (ALSWH) Cohort Australia 1996 50,000 Includes four cohorts of women: born between 1921-1926, 1946-1951, 1973-1978 and 1989-1995
Building a New Life in Australia: The Longitudinal Study of Humanitarian Migrants (BNLA) Cohort Australia 2013 2399 a longitudinal study of the settlement experience of humanitarian arrivals in Australia
Colombian Longitudinal Survey by Universidad de los Andes (ELCA) Panel Colombia 2010 15,363[5] Follows rural and urban households for increasing the comprehension of social and economic changes in Colombia
Avon Longitudinal Study of Parents and Children (ALSPAC) Cohort United Kingdom 1991 14,000 -
Born in Bradford Cohort United Kingdom 2007 12,500 -
1970 British Cohort Study (BCS70) Cohort United Kingdom 1970 17,000 Monitors the development of babies born in the UK in one particular week in April 1970
British Household Panel Survey Panel United Kingdom 1991 n/a Modeled on the US PFID study
Busselton Health Study Panel Australia 1966 10,000 -
Caerphilly Heart Disease Study Cohort United Kingdom 1979 2,512 Male subjects (Wales)
Canadian Longitudinal Study on Aging (CLSA-ÉLCV) Cohort Canada 2012 1,000 Planned as a 20-year study.[6]
Child Development Project Cohort United States 1987 585 Follows children recruited the year before they entered kindergarten in three cities: Nashville and Knoxville, TN and Bloomington, Indiana
Children of Immigrants Longitudinal Study (CILS) Cohort United States 1992 5,262 Florida
Congenital Heart Surgeons' Society (CHSS) Cohort Canada - 5,000 Various studies, managed by the Data Center Studies on Congenital Heart Diseases
Dunedin Multidisciplinary Health and Development Study Cohort New Zealand 1972 1,037 Participants born in Dunedin during 1972-73
Study of migrants and squatters in Rio’s Favelas Cohort Brazil 1968 n/a The work of Janice Perlman, reported in her book, Favela (2014)[7]
Footprints in TIme; the longitudinal study of Indigenous children Cohort Australia 2008 1680 Study of Aboriginal and Torres Strait Islander children in selected locations across Australia
Fragile Families and Child Wellbeing Study Cohort United States 1998 n/a Study being conducted in 20 cities
Framingham Heart Study Cohort United States 1948 5,209 Massachusetts
Genetic Studies of Genius Cohort United States 1921 1,528 The world's oldest and longest-running longitudinal study
Socio-Economic Panel (SOEP) Panel Germany 1984 12,000 -
Growing Up in Scotland (GUS) Cohort United Kingdom 2003 14,000[8] Scotland
Health and Retirement Study Cohort United States 1988 22,000 -
Household, Income and Labour Dynamics in Australia Survey Panel Australia 2001 25,000 -
Human Speechome Project Cohort United States 2005 1 Single participant was the son of the researcher, studying language development. Project concluded in 2008.
Growing Up in Australian; the longitudinal study of Australian children Cohort Australia 2004 10,000 -
Luxembourg Income Study (LIS) Cohort International 1983 n/a 30 countries
Midlife in the United States Cohort United States 1983 6,500 -
Manitoba Follow-Up Study (MFUS) Cohort Canada 1948 3,983 men Canada's largest and longest running investigation of cardiovascular disease and successful aging
Millennium Cohort Study (MCS) Cohort United Kingdom 2000 19,000 Study of child development, social stratification and family life
Millennium Cohort Study Cohort United States 2000 200,000 Evaluation of long-term health effects of military service, including deployments
Minnesota Twin Family Study Cohort United States 1983 17,000 (8,500 twin pairs) -
National Child Development Study (NCDS) Cohort United Kingdom 1958 17,000 -
National Longitudinal Surveys (NLS) Cohort United States 1979 NLSY79-12,686, NLSY97-approx. 9000 Includes 4 Cohorts: NLSY79 (Born 1957-64), NLSY97 (Born 1980-84), NLSY79 Children and Young Adults, National Longitudinal Surveys of Young Women and Mature Women (NLSW)
National Longitudinal Survey of Children and Youth (NLSCY) Cohort Canada 1994 35,795 Inactive since 2009.
National Health and Nutrition Examination Survey (NHANES) Cohort United States 1971 8,837 (since 1999) Continual since 1999
Pacific Islands Families Study Cohort New Zealand 2000 1,398 -
Panel Study of Belgian Households Panel Belgium 1992 11,000[9] -
Panel Study of Income Dynamics Panel United States 1968 70,000 Possibly the oldest household longitudinal surveys in the US
Rotterdam Study Cohort Netherlands 1990 15,000 Focus is on inhabitants of Ommoord, a suburb of Rotterdam
Seattle 500 Study Cohort United States 1974 500 Study of the effects of prenatal health habits on human development
Stirling County Study Cohort Canada 1952 639 Long term study epidemiology of psychiatric disorders. Two cohorts were studied (575 from 1952-1970; 639 from 1970-1992).[10]
Study of Health in Pomerania Cohort Germany 1997 15,000 Investigates common risk factors, sub-clinical disorders and manifest diseases in a high-risk population
Study of Mathematically Precocious Youth Cohort United States 1972 5,000 Follows highly intelligent people identified by age 13.
Irish Longitudinal Study on Ageing (TILDA) Cohort Ireland 2009 8,500 Studies health, social and financial circumstances of older Irish population
New Zealand Attitudes and Values Study - New Zealand 2009 n/a -
Seattle Longitudinal Study Cohort United States 1956 6,000 [11] -
Understanding Society: The UK Household Longitudinal Study Panel United Kingdom 2009 100,000 Incorporates the British Household Panel Survey
Up Series Cohort United Kingdom 1964 14 Documentary film project by Michael Apted
Study on Global Ageing and Adult Health (SAGE) Cohort International 2002 65,964 Studies the health and well-being of adult populations and the ageing process in six countries: China, Ghana, India, Mexico, Russian Federation and South Africa
    		 Wisconsin Longitudinal Study Cohort United States 1957 10,317 Follows graduates from Wisconsin high schools in 1957
    ONS Longitudinal Study Panel England and Wales 1974 (data from 1971) 1% sample of the population of England and Wales. The LS contains records on over 500,000 people usually resident in England and Wales at each point in time The sample comprises people born on one of four selected dates of birth and therefore makes up about 1% of the total population. The sample was initiated at the time of the 1971 Census, and the four dates were used to update the sample at the 1981,1991 2001 and 2011 Censuses and in routine event registrations. Fresh LS members enter the study through birth and immigration and existing members leave through death and emigration.

    Thus, the LS represents a continuous sample of the population of England and Wales, rather than a sample taken at one time point only. It now includes records for over 950,000 study members.

    In addition to the census records, the individual LS records contain data for events such as deaths, births to sample mothers, emigrations and cancer registrations.

    Census information is also included for all people living in the same household as the LS member. However, it is important to emphasise that the LS does not follow up household members in the same way from census to census.

    Support for potential users and more information available at CeLSIUS

    See also

    References

    1. ↑ Shadish, William R.; Cook, Thomas D.; Campbell, Donald T. (2002). Experimental and Quasi-Experimental Designs for Generalized Causal Inference (2nd ed.). Boston: Houghton Mifflin Company. p. 267. ISBN 0-395-61556-9.
    2. ↑ Carlson, Neil and et al. "Psychology the Science of Behavior", p. 361. Pearson Canada, United States of America
    3. ↑ Cherry, Kendra. "What Is Longitudinal Research?". experiments. About.com guide. Retrieved 22 February 2012.
    4. ↑ "What is the difference between a Panel Study and a Cohort Study?". Academia Stack Exchange. Retrieved 3 February 2016.
    5. ↑ Encuesta Longitudinal Colombiaba de la Universidad de los Andes - ELCA 2013
    6. ↑ Teotonio, Isabel (24 April 2012). "Landmark study on aging to follow 50,000 Canadians over the next two decades". Toronto Life (Toronto Star Newspapers Ltd.). Retrieved 28 July 2014.
    7. ↑ Favela: Longitudinal Multi-Generational Study of migrants and squatters in Rio’s Favelas, 1968-2014
    8. ↑ Growing Up in Scotland, Study dsign
    9. ↑ Panel Study of Belgian Households, Survey summary
    10. ↑ "Incidence of depression in the Stirling County Study: historical and comparative perspectives.". Psychol Med. (30(3)): 505–14. May 2000. Retrieved 23 May 2015.
    11. ↑ About the Seattle Longitudinal Study

    External links

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