Quiz Solution: Correlation and Regression Analysis, Quizzes of Statistics

Download Quiz Solution: Correlation and Regression Analysis and more Quizzes Statistics in PDF only on Docsity! Solution to Quiz 2 September 24, 2008 Problem 1 NO. Correlation does not imply a cause and effect relationship. So size of the hospital does not affect the length of stay of a patient. As a result the length of stay cannot be shortened by merely choosing a small hospital. In fact, the length of stay is mainly determined by the nature and condition of ailment of the patient. Problem 2 64%. For a liner relationship, the percentage explained by the explanatory variable is given by r2 = (0.8)2 = 0.64 = 64% Problem 3 0.79. The new variable U = a + X and V = a + Y . Let us denote the mean of X and Y by X̄ and Ȳ respective. Then the mean of U and V is respectively given by Ū = a + X̄, V̄ = a + Ȳ Since change in shift does not affect the standard deviation , the standard deviation of U and V will remain same as that of X and Y . Thus SU = SX , SV = SY 1