Longitudinal study

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A longitudinal study (or longitudinal survey, or panel study) is a research design that involves repeated observations of the same variables (e.g., people) over long periods of time (i.e., uses longitudinal data). It is often a type of observational study, although it can also be structured as longitudinal randomized experiment. [1]

Contents

Longitudinal studies are often used in social-personality and clinical psychology, to study rapid fluctuations in behaviors, thoughts, and emotions from moment to moment or day to day; in developmental psychology, to study developmental trends across the life span; and in sociology, to study life events throughout lifetimes or generations; and in consumer research and political polling to study consumer trends. 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, that is, the cohort effect. 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. 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.

Longitudinal studies can be retrospective (looking back in time, thus using existing data such as medical records or claims database) or prospective (requiring the collection of new data).[ citation needed ]

Cohort studies are one type of longitudinal study which sample a cohort (a group of people who share a defining characteristic, typically who experienced a common event in a selected period, such as birth or graduation) and perform cross-section observations at intervals through time. However, not all longitudinal studies are cohort studies, as longitudinal studies can instead include a group of people who do not share a common event. [3]

Advantages

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. [4] [ failed verification ]

Longitudinal studies do not require large numbers of participants (as in the examples below). Qualitative longitudinal studies may include only a handful of participants, [5] and longitudinal pilot or feasibility studies often have fewer than 100 participants. [6]

Disadvantages

Longitudinal studies are time-consuming and expensive. [7]

Longitudinal studies cannot avoid an attrition effect: that is, some subjects cannot continue to participate in the study for various reasons. Under longitudinal research methods, the reduction in the research sample will bias the remaining smaller sample.[ citation needed ]

Practice effect is also one of the problems: longitudinal studies tend to be influenced because subjects repeat the same procedure many times (potentially introducing autocorrelation), and this may cause their performance to improve or deteriorate.[ citation needed ]

Examples

Study nameTypeCountry or regionYear startedParticipantsRemarks
45 and Up Study CohortAustralia2006267,153The 45 and Up Study is a longitudinal study of participants aged 45 years and over in New South Wales conducted by the Sax Institute. Researchers are able to analyze Study data linked to MBS and PBS data, the NSW cancer registry, State hospitalizations, and emergency department visits and mortality data.

The Study is used by both researchers and policymakers to better understand how Australians are aging and using health services to prevent and manage ill-health and disability and guide health system decisions. 45 and Up is the largest ongoing study of healthy aging in the Southern Hemisphere.

Alzheimer's Disease Neuroimaging Initiative PanelInternational2004n/a–
Australian Longitudinal Study on Women's Health (ALSWH)CohortAustralia199650,000Includes four cohorts of women: born between 1921 and 1926, 1946–1951, 1973–1978 and 1989–1995
Nurses' Health Study CohortUnited States1976275,000Most expensive and largest observational health study in history
The Jyväskylä Longitudinal Study of Personality and Social Development, [8] (JYLS)CohortFinland1968369The sample was drawn from 12 complete school classes. Data has been collected when the participants were 8, 14, 20, 27, 33, 36, 42 and 50 years old.
Building a New Life in Australia : The Longitudinal Study of Humanitarian Migrants (BNLA) [9] CohortAustralia20132,399A longitudinal study of the settlement experience of humanitarian arrivals in Australia
Colombian Longitudinal Survey by Universidad de los Andes (ELCA) [10] PanelColombia201015,363 [11] Follows rural and urban households for increasing the comprehension of social and economic changes in Colombia
Avon Longitudinal Study of Parents and Children (ALSPAC)CohortUnited Kingdom199114,000–
Born in Bradford CohortUnited Kingdom200712,500–
1970 British Cohort Study (BCS70)CohortUnited Kingdom197017,000Monitors the development of babies born in the UK in one particular week in April 1970
British Doctors Study CohortUnited Kingdom195140,701Monitored the health of British male doctors. It provided convincing evidence of the link between smoking and cancer.
British Household Panel StudyPanelUnited Kingdom19915,500 households (~10,000 individuals)Modeled on the US Panel Study of Income Dynamics PSID study
Busselton Health Study [12] PanelAustralia196610,000–
Caerphilly Heart Disease Study CohortUnited Kingdom19792,512Male subjects (Wales)
Canadian Longitudinal Study on Aging (CLSA-ÉLCV) [13] CohortCanada 2011 51,388 [14] All research participants will be followed until 2033 or death. [15]
Child Development Project [16] CohortUnited States1987585Follows children recruited the year before they entered kindergarten in three US cities: Nashville and Knoxville, Tennessee, and Bloomington, Indiana
Children of Immigrants Longitudinal Study (CILS)CohortUnited States19925,262Florida
Congenital Heart Surgeons' Society (CHSS)CohortCanada–5,000Various studies, managed by the Data Center Studies on Congenital Heart Diseases
Dunedin Multidisciplinary Health and Development Study CohortNew Zealand19721,037Participants born in Dunedin during 1972–73
Study of migrants and squatters in Rio's FavelasCohortBrazil1968n/aThe work of Janice Perlman, reported in her book Favela (2014) [17]
Footprints in Time; the longitudinal study of Indigenous children [18] CohortAustralia20081,680Study of Aboriginal and Torres Strait Islander children in selected locations across Australia
Fragile Families and Child Wellbeing Study CohortUnited States1998n/aStudy being conducted in 20 cities
Framingham Heart Study CohortUnited States19485,209Massachusetts
Genetic Studies of Genius CohortUnited States19211,528The world's oldest and longest-running longitudinal study
Socio-Economic Panel (SOEP)PanelGermany198412,000–
Growing Up in Ireland (GUI)CohortThe Republic of Ireland20068,000 children
10,000 infants		Growing Up in Ireland is an Irish Government-funded study of children being carried out jointly by the Economic and Social Research Institute and Trinity College Dublin. The study started in 2006 and follows the progress of two groups of children: 8,000 9-year-olds (Child Cohort/Cohort '98) and 10,000 9-month-olds (Infant Cohort/Cohort '08).
Growing Up in New Zealand (GUiNZ)CohortNew Zealand20096,846 children

GUiNZ is New Zealand's largest ongoing longitudinal study. It follows approximately 11% of all NZ children born between 2009 and 2010. [19] The study aims to look in depth at the health and well-being of children (and their parents) growing up in NZ.

Growing Up in Scotland (GUS)CohortScotland200314,000Scotland
Health and Retirement Study CohortUnited States198822,000–
Household, Income and Labour Dynamics in Australia Survey PanelAustralia200125,000–
Grant Study CohortUnited States1939268A 75-year longitudinal study of 268 physically and mentally healthy Harvard college sophomores from the classes of 1939–1944.
Growing Up in Australia; the longitudinal study of Australian children [20] CohortAustralia200410,000–
Midlife in the United StatesCohortUnited States19836,500–
Manitoba Follow-Up Study (MFUS)CohortCanada19483,983 menCanada's largest and longest running investigation of cardiovascular disease and successful aging
Millennium Cohort Study (MCS)CohortUnited Kingdom200019,000Study of child development, social stratification, and family life
Millennium Cohort Study CohortUnited States2000200,000Evaluation of long-term health effects of military service, including deployments
Minnesota Twin Family Study CohortUnited States198317,000 (8,500 twin pairs)–
National Child Development Study (NCDS)CohortUnited Kingdom195817,000–
National Educational Panel Study (NEPS)CohortGermany200960,000Study on the development of competencies, educational processes, educational decisions, and returns to education in formal, nonformal, and informal contexts throughout the life span
National Longitudinal Surveys (NLS)CohortUnited States197912,686 (NLSY79),
9,000 (approx., NLSY97)		Includes four 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)CohortCanada199435,795Inactive since 2009
National Health and Nutrition Examination Survey (NHANES)CohortUnited States19718,837 (since 1999)Continual since 1999
Nature vs Nurture studyCohortUnited States196011 [22] Concluded in 1980. Controversial study by Peter B. Neubauer of twins and triplets separated at birth. Never published.
Pacific Islands Families Study CohortNew Zealand20001,398–
Panel Study of Belgian Households [23] PanelBelgium199211,000 [24] –
Panel Study of Income Dynamics PanelUnited States196870,000Possibly the oldest household longitudinal survey in the US
The Raine Study CohortAustralia19895,768 (Gen1 + Gen2)
750 (Gen3)
100 (Gen0)		The Raine Study is based in Perth, Western Australia. It has followed the same group of pregnant women (Gen1) and their babies (Gen2) who were born into the study between 1989 and 1992. Its original aim was to investigate the benefits of more frequent ultrasound scans on infant health. [25] It now studies the impact that early life factors (from the womb onwards) have on health throughout life. [26] The Raine Study now includes 4 generations of cohort members.
Rotterdam Study CohortNetherlands199015,000Focus is on inhabitants of Ommoord, a suburb of Rotterdam
Seattle 500 Study CohortUnited States1974500Study of the effects of prenatal health habits on human development
Stirling County StudyCohortCanada1952639Long-term study epidemiology of psychiatric disorders. Two cohorts were studied (575 from 1952 to 1970; 639 from 1970 to 1992). [27]
Study of Health in Pomerania CohortGermany199715,000Investigates common risk factors, sub-clinical disorders and manifest diseases in a high-risk population
Study of Mathematically Precocious Youth CohortUnited States19725,000Follows highly intelligent people identified by age 13.
Survey of Health, Ageing, and Retirement in Europe (SHARE)PanelEurope2002120,000Multidisciplinary and cross-national panel database of micro data on health, socio-economic status and social and family networks of individuals aged 50 or over
Irish Longitudinal Study on Ageing (TILDA)CohortIreland20098,500Studies health, social and financial circumstances of the older Irish population
New Zealand Attitudes and Values Study –New Zealand2009n/a–
Seattle Longitudinal Study CohortUnited States19566,000 [28] –
Understanding Society: The UK Household Longitudinal Study PanelUnited Kingdom2009100,000Incorporates the British Household Panel Study
Up Series CohortUnited Kingdom196414Documentary film project by Michael Apted
Study on Global Ageing and Adult Health (SAGE)CohortInternational200265,964Studies 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 [29] CohortUnited States195710,317Follows graduates from Wisconsin high schools in 1957
ONS Longitudinal Study [30] [31] PanelEngland and Wales1974 (data from 1971)500,000 (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 a 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 emphasize 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
Scottish Longitudinal Study (SLS) [32] PanelScotland1991274,000 (comprises 5.3% sample of the Scottish population, with records on approximately 274,000 individuals using 20 random birthdates)The SLS is a large-scale linkage study built upon census records from 1991 onwards, with links to vital events (births, deaths, marriages, emigration); geographical and ecological data (deprivation indices, pollution, weather); primary and secondary education data (attendance, Schools Census, qualifications); and links to NHS Scotland ISD datasets, including cancer registrations, maternity records, hospital admissions, prescribing data and mental health admissions. The research potential is considerable. The SLS is a replica of the ONS Longitudinal Study but with a few key differences: sample size, commencement point and the inclusion of certain variables. The SLS is supported and maintained by the SLS Development & Support Unit with a safe-setting at the National Records of Scotland in Edinburgh. Further information and support for potential users is available at SLS-DSU
Northern Ireland Longitudinal Study (NILS) [33] PanelNorthern Ireland2006500,000 (comprises about 28% of the Northern Ireland population and approximately 50% of households).The NILS is a large-scale, representative data-linkage study created by linking data from the Northern Ireland Health Card Registration system to 1981, 1991, 2001 and 2011 census returns and to administrative data from other sources. These include vital events registered with the General Register Office for Northern Ireland (such as births, deaths, and marriages) and the Health Card registration system migration events data. The result is a 30-year-plus longitudinal data set which is regularly being updated. In addition to this rich resource, there is also the potential to link further Health and Social care data via distinct linkage projects (DLPs). The NILS is designed for statistics and research purposes only and is managed by the Northern Ireland Statistics and Research Agency under Census legislation. The data are de-identified at the point of use; access is only from within a strictly controlled 'secure environment' and governed by protocols and procedures to ensure data confidentiality.
Early Childhood Longitudinal Study (ECLS)United States

See also

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  11. ↑ Encuesta Longitudinal Colombiaba de la Universidad de los Andes – ELCA 2013 [ permanent dead link ]
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  18. ↑ "Overview of Footprints in Time – The Longitudinal Study of Indigenous Children (LSIC)". Department of Social Services, Australian Government. Retrieved 1 December 2016.
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  29. ↑ "Wisconsin Longitudinal Study Homepage" . Retrieved 1 December 2016.
  30. ↑ "ONS Longitudinal Study". Archived from the original on 2015-10-10. Retrieved 2015-12-08.
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  33. ↑ "Queen's University Belfast – NILS Research Support Unit – NILS Research Support Unit" . Retrieved 1 December 2016.
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