D Question 1 1 pts What is the main purpose of regression? O It simplifies statistical calculations and makes it easier to manually compute them. O It potentially provides a mathematical model that can be used to make predictions. O It excludes undesired data from the sample set. O It visually shows the relationships between variables. D Question 2 1 pts What is a correlation coefficient? A number that goes after the independent variable in a linear equation. O A number that measures the strength and direction of a linear relationship between two variables. O A number that measures the slope of a relationship between variables. O A number that tells you how linear a relationship is.D Question 3 1 pts What is the coefficient of determination? O A number that is predetermined in a linear regression analysis, reflecting your confidence level. O A number that indicates the statistical significance of a relationship between two variables. O A measure of how determined you are in finishing your degree. O A measure of the percentage of variation of the dependent variable that is explained by the regression line and the independent variable. D Question 4 1 pts What is the difference between explained and unexplained variation? O Explained variation is variation obtained from the regression relationship whereas unexplained variation is variation due to chance. O Explained variation is when people explain what is variation is whereas unexplained variation is unexplainable variation. O Explained variation is the correlation between the variable and the regression line whereas unexplained variation is the outlier data that is not captured by the regression line. O Explained variation is the variation due to chance whereas unexplained variation is variation obtained from the regression relationship.D Question 5 1 pts Choose all elements from below that would help you evaluate the overall validity of a regression model. O Visual inspection of regression plots Standard error Slope coefficient O p value O Correlation matrices Root mean squared error Coefficient of determination (r2)Question 6 0.9 pts Identify the correct statement from below. O Polynomial models are generally superior to logarithmic models. O To calculate the correlation coefficient, you just square the coefficient of determination. O The p-value is the ultimate metric we should use to determine the quality of a regression model. O It is convenient to include as many variables as possible in a multiple regression model so its prediction accuracy increases. O In a multiple regression model evaluation, a predictor with an unsatisfactory p-value should be eliminated from the model