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 Analysis
Famous quotes containing the words power and, power, sample, size and/or calculations:
“Power and violence are opposites; where the one rules absolutely, the other is absent. Violence appears where power is in jeopardy, but left to its own course it ends in power’s disappearance.”
—Hannah Arendt (1906–1975)
“The dying man doesn’t struggle much and he isn’t much afraid. As his alkalies give out he succumbs to a blest stupidity. His mind fogs. His will power vanishes. He submits decently. He scarcely gives a damn.”
—H.L. (Henry Lewis)
“All that a city will ever allow you is an angle on it—an oblique, indirect sample of what it contains, or what passes through it; a point of view.”
—Peter Conrad (b. 1948)
“To believe her limited in range because she was harmonious in method is as sensible as to imagine that when the Atlantic Ocean is as smooth as a mill-pond it shrinks to the size of a mill-pond.”
—Rebecca West (1892–1983)
“Heaven’s calculations don’t follow man’s calculations.”
—Chinese proverb.