Ceteris paribus

from Wikipedia, the free encyclopedia

Ceteris paribus means “under otherwise identical conditions”. It plays a big role in experiments . If you want to find out how a first variable affects a second, you look at several situations in which both arise. Ceteris paribus now demands that all other conditions must remain the same. This is to rule out that a third, fourth, etc. variable influences the observed effect, thus ensuring that the results of the investigation exclusively describe the relationship between the dependent and independent variable .

Ceteris paribus is an essential requirement for internal validity . Abbreviations for the Latin expression are cp and cet. par.


In order to be able to draw causal conclusions from experiments , the effects measured with the dependent variable must be clearly attributable to the manipulation of the independent variable. Other influences must therefore be excluded or kept constant. This ceteris paribus clause was also called the method of difference by John Stuart Mill .

For the social sciences, such as If, for example, Imre Lakatos' writings on the philosophy of science suggest, it is necessary to adapt the ceteris paribus clause to the epistemological modifications of the 20th century (see, inter alia, the positivism dispute ). The latter must also be observed in the behavioral sciences for reasons of intersubjectivity , which also always apply to researchers themselves. The ceteris-paribus-distributionibus approach is an important addition to empirical social sciences: disruptive influences can never be completely eliminated; It is therefore important to ensure , through the correct choice of the error terms in models and in addition to the usual controls, that these biases are distributed to approximately the same extent over the test conditions or participants in the investigation.


In an experiment , only one influencing variable is changed, while all others are kept constant in order to be able to precisely determine their influence. The ceteris paribus clause thus represents a way of considering and evaluating simplified models of reality with regard to the effects of changes in individual parameters.

If, however, it is not checked whether the model simplifications still adequately describe the relevant facts when the results change the model requirements, then the (thought) experiment can be wrong or useless. The model can only be used if the result changes the conditions only insignificantly or not at all. However, this test was ignored for many models, which are still published as useful, although the requirement of ceteris paribus (“assuming that all other general conditions [premises] remain the same except the [previously]] mentioned other framework conditions) is violated .


The price of a good is, in addition to z. B. the demand, influenced by many other factors, such as the supply and prices of other goods. If you want to find out, for example, which factors influence the formation of the equilibrium price in which way , only one factor may be changed per experiment. This corresponds to the ceteris paribus conditions, since all factors - with the exception of the factor to be checked - remain the same.

If the influence of the various price-forming factors on the equilibrium price can be formulated as a mathematical function of several independent variables, the influence of each of them on the equilibrium price can be determined with the help of so-called partial derivatives , in which only one of the variables is considered variable, all others are treated as constant.


  • All other things being equal. In: Günther Wöhe: Introduction to general business administration. 17th edition. Munich 1990, ISBN 3-8006-1472-3 , p. 34ff.
  • Rainer Fischbach, Klaus Wollenberg: Economics 1: Introduction and Basics. Oldenbourg Verlag, Munich 2007, ISBN 3-486-58307-7 , p. 53 ( limited preview in the Google book search - definition and presentation of the ceteris paribus clause).
  • Persky, Joseph: Retroperspectives: Ceteris Paribus . In: The Journal of Economic Perspectives . tape 4 , no. 2 , 1990, p. 187-193 , JSTOR : 1942898 .
  • Ekkehart Schlicht : Fundamentals of Economic Analysis . Rowohlt, 1977, ISBN 3-499-21112-2 , chap. 1 ( uni-muenchen.de [PDF]).

Web links

Wiktionary: ceteris paribus  - explanations of meanings, word origins, synonyms, translations
Wiktionary: Ceteris paribus clause  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Willi Hager: The fallibility of empirical data and the need to control the probabilities of wrong decisions. In: Journal of Psychology. Volume 214, No. 1, 2006, doi: 10.1026 / 0044-3409.214.1.10 , p. 12.