ceteris paribus

The Latin expression ceteris paribus ( cp abbreviation or cet. Par. ) Literally means " at the same other [ things or circumstances ] ", which means " other things being equal ". This reservation is also called ceteris paribus clause. He plays primarily in connection with experiments a role and then " under the condition that all other mentioned except the (previously ) variables remain the same ." This is an essential requirement for internal validity.

Importance

In order to draw causal conclusions from experiments that measured with the dependent variable effects must be clearly attributed to the manipulation of the independent variable. Other factors must therefore be excluded or kept constant. This ceteris paribus clause was described by John Stuart Mill as a method of difference.

Application

In one experiment is always changing just one influence quantity, while all others are kept constant in order to accurately determine their influence can. The ceteris paribus clause thus represents a way to consider simplified models of reality in terms of the effects of changes in individual parameters and evaluate.

If not checked whether the model simplifications the facts in question will still adequately describe when the model assumptions are changed by the results, it can be wrong or useless the ( thought ) experiment. Only if the result of the conditions only marginally or not at all changed, the model is useful. This test but was left on many models aside, which are still published as a useful, although this ceteris paribus is violated "under the assumption that all of the above except the (previously ) other conditions ( assumptions ) remain the same. ".

Example

The price of a product is, in addition, for example, demand, influenced by many other factors, such as the offer and the prices of other goods. If you now wish to find out in what way to take what factors on the formation of the equilibrium price impact, for example, only one factor per experiment can always be changed. This corresponds to the ceteris paribus conditions, since all - remain the same factors - except for the ones to check.