Power and Sample Size Calculations
There are no generally agreed methods for relating the number of observations versus the number of independent variables in the model. One rule of thumb suggested by Good and Hardin is, where is the sample size, is the number of independent variables and is the number of observations needed to reach the desired precision if the model had only one independent variable. For example, a researcher is building a linear regression model using a dataset that contains 1000 patients . If he decides that five observations are needed to precisely define a straight line, then the maximum number of independent variables his model can support is 4, because
.
Read more about this topic: Regression Estimation
Famous quotes containing the words power and, power, sample, size and/or calculations:
“A state that denies its citizens their basic rights becomes a danger to its neighbors as well: internal arbitrary rule will be reflected in arbitrary external relations. The suppression of public opinion, the abolition of public competition for power and its public exercise opens the way for the state power to arm itself in any way it sees fit.... A state that does not hesitate to lie to its own people will not hesitate to lie to other states.”
—Václav Havel (b. 1936)
“Giving money and power to government is like giving whiskey and car keys to teenage boys.”
—P.J. (Patrick Jake)
“The present war having so long cut off all communication with Great-Britain, we are not able to make a fair estimate of the state of science in that country. The spirit in which she wages war is the only sample before our eyes, and that does not seem the legitimate offspring either of science or of civilization.”
—Thomas Jefferson (1743–1826)
“Delusions that shrink to the size of a woman’s glove,
Then sicken inclusively outwards:
. . . the incessant recital
Intoned by reality, larded with technical terms,
Each one double-yolked with meaning and meaning’s rebuttal:
For the skirl of that bulletin unpicks the world like a knot....”
—Philip Larkin (1922–1986)
“What, really, is wanted from a neighborhood? Convenience, certainly, an absence of major aggravation, to be sure. But perhaps most of all, ideally, what is wanted is a comfortable background, a breathing space of intermission between the intensities of private life and the calculations of public life.”
—Joseph Epstein (b. 1937)