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 young man, be his merit what it will, can never raise himself; but must, like the ivy round the oak, twine himself round some man of great power and interest.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“The only power deserving the name is that of masses, and of governments while they make themselves the organ of the tendencies and instincts of masses.”
—John Stuart Mill (1806–1873)
“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)
“O hideous little bat, the size of snot,
With polyhedral eye and shabby clothes,”
—Karl Shapiro (b. 1913)
“Heaven’s calculations don’t follow man’s calculations.”
—Chinese proverb.