Will Rogers phenomenon

The Will Rogers phenomenon (English stage migration, ) is an effect in the averaging of groups: By changing an element from one to the other group, the mean can rise in both groups ( or fall ).

Statisticians speak sometimes laconic by a criminal (data) association.

It was named after Will Rogers ( humorist and philosopher), who said: ". When the Okies left Oklahoma and moved to California, They raised the average intelligence level in Both states" ( German: "When the people of Oklahoma moved to California, they raised the average intelligence in both states. " )

Example

In the municipality of A Village residents have a median income of $ 2.5 thalers, which in B- village 7 dollars. Attracts Mr. X from B- town with an income of five thalers to A Village, increases in both villages and the median income, as

  • Mr. X with his meager income the average moved into B- town down, and
  • In A Village raised by his above-average income.

In figures previously:

  • A = {1, 2, 3, 4}, the mean = 2.5
  • B = {5, 6, 7, 8, 9 }, mean = 7

Moves you but the 5 from B to A, so you get

  • A = {1, 2, 3, 4, 5}, Average = 3
  • B = { 6, 7, 8, 9 }, mean = 7.5

As you can see, increase the mean values ​​of both quantities. Since the set of all values ​​of the two quantities did not change, the common mean is unchanged 5

Early detection of disease

The Will Rogers phenomenon also has effects in science: For an improved therapy is a statistic about the life expectancy of cancer only through improved diagnostics faked, such as in the early detection of diseases.

" The tumors are classified into large and small; when the diagnosis method improves, more parts of each tumor discovered, and tumors that would have been previously considered small, are recognized as major. Thus, the most dangerous specimens are removed from the group of small tumors and inserted as harmless specimens in the group of large tumors - for both groups the curability seems to improve. Also, now even very small tumors are detected, which further increases the measured curability. "

Digital Object Identifier
744970
de