Longitudinal study

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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 a type of observational study. 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 same characteristics are compared,[1] longitudinal studies track the same people, and therefore the differences observed in those people are less likely to be the result of cultural differences across generations. Because of this benefit, longitudinal studies make observing changes more accurate, and they 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.

Because most 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. But 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 by virtue 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.[2]

Longitudinal studies allow social scientists to distinguish short from long-term 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 using one-off cross-sectional studies.

Types of longitudinal studies include cohort studies and panel studies. Cohort studies sample a cohort, defined as a group experiencing some event (typically birth) in a selected time period, and studying them at intervals through time. Panel studies sample a cross-section, and survey it at (usually regular) intervals.

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[edit]

Study name Type Country or Region Year started Participants Remarks
Alzheimer's Disease Neuroimaging Initiative Panel International 2004 n/a -
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 50,000 Planned as a 20-year study.[3]
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 were all born in 1972
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)[4]
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[5] 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.
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 -
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 Icludes 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 -
Pacific Islands Families Study Cohort New Zealand 2000 1,398 -
Panel Study of Belgian Households Panel Belgium 1992 11,000[6] -
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
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
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 [7] -
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

See also[edit]

References[edit]

  1. ^ Carlson, Neil and et al. "Psychology the Science of Behavior", p. 361. Pearson Canada, United States of America
  2. ^ Cherry, Kendra. "What Is Longitudinal Research?". experiments. About.com guide. Retrieved 22 February 2012. 
  3. ^ 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. 
  4. ^ Favela: Longitudinal Multi-Generational Study of migrants and squatters in Rio’s Favelas, 1968-2014
  5. ^ Growing Up in Scotland, Study dsign
  6. ^ Panel Study of Belgian Households, Survey summary
  7. ^ About the Seattle Longitudinal Study

External links[edit]