Floor effect

With ground effect ( engl. floor effect ) is called no longer in the empirical social sciences but also in psychology, the phenomenon that with the help of an instrument (such as a psychological test ) low benefits of a different quality in the empirical relative in the numerical relatively occur as different as both low and medium good performances, even all the services, the minimum speed characteristic value is assigned in the worst case and thus suffers the selectivity of the resulting indexes. Since there may be knowledge to solve the problems is needed, blurs the empirical validity of such a test, since both intelligence strong and weak subjects possess this intelligence does not necessarily.

Example

Where is a fictional intelligence test, maintain its creator, so to be able to reliably cover the IQ range of 50 to 150 IQ points. The test consists only of several smaller mathematical tests in which the subject is asked to continue the given according to logical criteria row of numbers. The lightest of numbers have the following form:

• A) 2 7 1 8 2 8 1 8 2 8 4 5 9 0

(Solution: 4, 14 decimal of the Euler number e )

• B ) 6 28 496 8,128 33,550,336

( Solution: 8589869056, sixth perfect number )

• C ) 146511208 472335975 534494836

(Solution: 912 985 153, last 9 digits Armstrong number), etc.

Since these tests are probably many, even intelligence strong test takers can not be solved as long as they do not have a subject-specific academic knowledge of mathematics, but intelligence weak subjects should certainly have problems, probably a low score after working through all the tests is achieved by almost all people. The test results of most thus reach the " bottom " (English " floor" ) and the desired significance takes damage. The floor effect exists not only in empirical social research, but also in other sciences.