The term personal equation, in 19th- and early 20th-century
science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
, referred to the idea that every individual observer had an inherent
bias
Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, ...
when it came to
measurement
Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events.
In other words, measurement is a process of determining how large or small a physical quantity is as compared ...
s and
observation
Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The ...
s.
Astronomy
The term originated in
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
, when it was discovered that numerous observers making simultaneous observations would record slightly different values (for example, in recording the exact time at which a
star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
crossed the wires of a
reticule
Reticule can refer to:
* Reticle, fine lines in the eyepiece of a sighting device
* Reticule (handbag)
A reticule, also known as a ridicule or indispensable, was a type of small handbag or purse, similar to a modern evening bag, used mainly f ...
in a
telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...
), some of which were of a significant enough difference to afford for problems in larger calculations.
The existence of the effect was first discovered when, in 1796, the
Astronomer Royal
Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834.
The post ...
Neville Maskelyne dismissed his assistant Kinnebrooke because he could not better the error of his observations relative to Maskelyne's own values. The problem was forgotten and only analysed two decades later by
Friedrich Wilhelm Bessel
Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method ...
at
Königsberg Observatory
Koenigsberg Observatory (german: Sternwarte Königsberg; Königsberger Universitätssternwarte; obs. code: 058) was an astronomical observatory and research facility which was attached to the Albertina University in Königsberg, what is now Kal ...
in
Prussia
Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an em ...
. Setting up an experiment to compare the values, Bessel and an assistant measured the times at which several stars crossed the wires of a reticule in different nights. Compared to his assistant, Bessel found himself to be ahead by more than a second.
In response to this realization, astronomers became increasingly suspicious of the results of other astronomers and their own assistants and began systematic programs to attempt to find ways to remove or lessen the effects. These included attempts at the automation of observations (appealing to the presumed
objectivity of machines), training observers to try to avoid certain known errors (such as those caused by lack of
sleep
Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
), developing machines that could allow multiple observers to make observations at the same time, the taking of redundant data and using techniques such as the
method of least squares
The method of least squares is a standard approach in regression analysis to approximate the solution of overdetermined systems (sets of equations in which there are more equations than unknowns) by minimizing the sum of the squares of the res ...
to derive possible values from them, and trying to quantify the biases of individual workers so that they could be subtracted from the data. It became a major topic in
experimental psychology
Experimental psychology refers to work done by those who apply experimental methods to psychological study and the underlying processes. Experimental psychologists employ human participants and animal subjects to study a great many topics, in ...
as well, and was a major motivation for developing methods to deal with
error
An error (from the Latin ''error'', meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake. The etymology derives from the Latin term 'errare', meaning 'to stray'.
In statistics ...
in astronomy.
James and Jung
William James
William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States.
James is considered to be a leading thinker of the lat ...
helped move the concept of the personal equation from astronomy to social science, arguing that theoretical preconceptions and personal knowledge could lead investigators to wild interpretations based largely on their own personal equations.
Carl Jung
Carl Gustav Jung ( ; ; 26 July 1875 – 6 June 1961) was a Swiss psychiatrist and psychoanalyst who founded analytical psychology. Jung's work has been influential in the fields of psychiatry, anthropology, archaeology, literature, philo ...
took up the idea in his book
Psychological Types, arguing that in psychology "one sees what one can best see oneself". He continued to wrestle in later writings with the problems of psychological solipsism and
infinite regress
An infinite regress is an infinite series of entities governed by a recursive principle that determines how each entity in the series depends on or is produced by its predecessor. In the epistemic regress, for example, a belief is justified beca ...
this potentially posed, and considered every therapist should have at least a good working knowledge of his or her own personal equation.
[Shamdasani]
See also
*
Source criticism
Source criticism (or information evaluation) is the process of evaluating an information source, i.e.: a document, a person, a speech, a fingerprint, a photo, an observation, or anything used in order to obtain knowledge. In relation to a given p ...
*
Theory‐ladenness of observations In the philosophy of science, observations are said to be "theory-laden" when they are affected by the theoretical presuppositions held by the investigator. The thesis of theory-ladenness is most strongly associated with the late 1950s and early 1 ...
References
{{Reflist
History of astronomy
Error
Measurement
Experimental bias