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:
“Every diminution of the public burdens arising from taxation gives to individual enterprise increased power and furnishes to all the members of our happy confederacy new motives for patriotic affection and support.”
—Andrew Jackson (1767–1845)
“Now different races and nationalities cherish different ideals of society that stink in each other’s nostrils with an offensiveness beyond the power of any but the most monstrous private deed.”
—Rebecca West (1892–1983)
“As a rule they will refuse even to sample a foreign dish, they regard such things as garlic and olive oil with disgust, life is unliveable to them unless they have tea and puddings.”
—George Orwell (1903–1950)
“Great causes are never tried on their merits; but the cause is reduced to particulars to suit the size of the partizans, and the contention is ever hottest on minor matters.”
—Ralph Waldo Emerson (1803–1882)
“Heaven’s calculations don’t follow man’s calculations.”
—Chinese proverb.