A long-term study is a methodologically -scale, often experimental study on the empirical extraction of information (data ), the study includes an extraordinarily long period of time, since the observed phenomenon rarely occurred or his complete transformation takes place extremely slowly. In the investigation period, the experimental set-up is usually not changed.
A distinction is made in long-term investigation between the long-term study (ie the "pure observational study ", for example, sociology, psychology, medicine in the field ), there is no intervention in the in the observed system and the long-term experiment ( in the sense of " intervention study "). Be distinguished from long-term experiment is again the mere scientific observation (in the sense of a " long-term measurement ", as for example in astronomy, geology, biology is common).
Long-term studies are needed in many sciences and carried out, for example in the natural sciences, agricultural sciences and engineering, medicine, psychology and sociology. In medicine, one often speaks instead of long-term study also often of cohort study in the sociology of contrast, longitudinal study.
Long-term studies face unique, seasonal challenges:
- Personnel: The duration of long-term studies generally exceeds the time periods in the sciences, in which master, diploma or doctoral theses are written; self- care by the Chair or permanently set scientific personnel can often not be guaranteed for long-term studies.
- Stability of the measurement system: During the study period must be ensured that the experiments performance, ie the behavior and properties of the measurement system (eg, programs ( software) or equipment (hardware ) ) does not change, so that a consistent data acquisition is guaranteed.
- Long-term archiving: The applicant must have the entire study period, which may comprise several decades, sustainable data archiving can be ensured.
- Attractiveness: Long-term studies have not, by definition short term determinable scientific results, but that makes them unattractive to scientists who need to position themselves strategically for the sake of personal career planning and are therefore particularly attracted to such areas of science that develop dynamic and promising possibilities for success in the short term.
Despite these inherent difficulties long-term studies are carried out, because they often offer the only possibility of verification or falsification of hypotheses on different scientific fields.
The most impressive example of this are perhaps the long-term measurements of various transnational institutions in meteorology over a period spanning many decades, which now form the basis for the international debate about global warming.
Examples of long-term studies
- The (initially sponsored by the department store millionaire WT Grant and therefore named after him ) Grant study, which are since 1939 a total of 268 Harvard graduates in 1910, up from studying until retirement medical and psychological monitoring (corresponding to the start of the study subjects male, white and have U.S. citizenship ).
- The scale at the Faculty of Agriculture and Horticulture, Humboldt -Universität zu Berlin Duration field experiment D III for the use of land, was created by Kurt Opitz in 1923 to the newly established experimental field in Berlin- Dahlem purely with the aim of detecting a mobilization of soil phosphoric acid by to provide agronomic measures and at the same time to examine the effectiveness of differentiated phosphorus fertilization under these conditions, and ran up to the recent time.
- The DONALD study (Abbreviation for: Nutritional and Anthropometric Longitudinally Designed DOrtmund ), the Research Institute of Child Nutrition ( FKE) was started in 1985. This is an open-label long-term cohort study, as many infants are newly recruited annually, as young adults completing the core study. Are planned close-knit research from infancy to adulthood with detailed data collection on nutrition, growth, development, metabolism and health status.
- Meteorological measurements at the long-term climate and weather station of the Research Center Jülich, where meteorological measurements and climatological observations are carried out regularly since 1961.
- An example of the first long-term observation of the weather is the body of Kilian 1513-1531 handwritten guided Weather Diary, motivated probably by the monastery's own agriculture. He wore his observations daily in a ephemerides ( "how it all day, smelled, or wan it rained "); right next to the indication of the position of the heavenly bodies on the day he recorded the weather in keywords, such as lightning, hail, floods, cold spells. The effects of the weather, he noted at the bottom and at the top of each page, in particular the development of agriculturally important crops: sowing, flowering, harvesting, but also consequences such as a control.
- Long-term measurements over the period from 1992 to 2003 in East Antarctica, where an increase of the ice sheet was measured by 45 cm, which agrees with the fact that the increased evaporation over the oceans leads to increased snowfall in the cold East Antarctica.
- Long-term measurements of radiocarbon in atmospheric carbon dioxide at the University of Heidelberg for the observation of the increase of the greenhouse gas since the 1990s.
- Decades of measurements of the geomagnetic field with the Adolf- Schmidt- Observatory for Geomagnetism at the GFZ Potsdam.
- Geodetic long-term studies on the lunar surface during the years 1969-1977 by the Apollo Lunar Surface Experiments Package ( ALSEP ), a scientific equipment complex, with the - extremely accurate distance measurements of the moon are made possible by the earth through time measurements of a laser pulse - still. In 2011 it was announced that had a new analysis of about 13,000 recorded moonquakes the seismometer to new results with respect to the lunar interior, in particular the detection of a liquid core out.
- The astronomical research programs by Cuno Hoffmeister at Sonneberg Observatory, which were started in 1924 and of which the " Sonneberg sky watch" which is based on the idea of Paul Guthnicks to monitor the entire northern hemisphere by means of astrophotography, runs to this day.
- The Voyager program of NASA to explore the outer solar system and interstellar space, which includes the research mission of the two space probes Voyager 1 and Voyager 2, which launched in 1977 and still active on their way through space. The Voyager 1 spacecraft is now in the outer region of the heliosphere and approaches the boundary of our solar system, the heliopause.
- High-energy physics experiments at the HERA particle accelerator at DESY from 1994 to 2007, which in turn were accompanied by various measurements for calibration and quality assurance, such as through experiments for measuring the properties of the optical components in the ZEUS detector over a period of 17 years ( was concerned with determining a very weak but systematic turbidity of the scintillators of the calorimeter ).
- The " pitch drop" experiment from the year 1927, the University of Queensland in Australia, which measures the flow of viscous liquids. For example. melts bitumen at room temperature is extremely slow, so that several years before to form a single drop.
This list can be extended by a number of other examples of long-term studies of the sciences.
As a musical long-term experiment may to some extent apply to the piece of music ORGAN ² / ASLSP for organ by John Cage in 1987. The abbreviation stands for ASLSP as slow as possible and is the instruction to play the eight-sided score as slowly as possible. Since 2001, there is so far in the St. Burchardi church in Halberstadt slowest and long -lasting piece of music in the world - in a planned total length of 639 years - to the performance.