During its manufacture, a product is subjected to four different tests in sequential order. An efficiency expert claims that the fourth (and last) test is unnecessary since its results can be predicted based on the first three tests. To test this claim, multiple regression will be used to model Test4 score (y), as a function of Test1 score (x1), Test 2 score (x2), and Test3 score (x3). [Note: All test scores range from 200 to 800, with higher scores indicative of a higher quality product.] Consider the model: E(y) = B1 + B1x1 + B2x2 + B3x3 The first-order model was fit to the data for each of 12 units sampled from the production line. The results are summarized in the printout. SOURCE DF F VALUE PROB>F SS MS MODEL ERROR TOTAL 3 151417 50472 18.16 .0075 22231 2779 12 173648 ROOT MSE 52.72 R-SQUARE 0.872 DEP MEAN 645.8 ADJ R-SQ 0.824 PARAMETER STANDARD T FOR 0 VARIABLE ESTIMATE ERROR PARAMETER =0 PROB> ITI 0. S85 0.039 0.005 0.004 0. 15 11.98 0.2745 INTERCEPT S0.50 x1(TESTI) 0.1111 2.47 X2(TEST2) X3(TEST3) Suppose the 95% confidence interval for B 3 is (.15, .47). Which of the following statements is incorrect? O We are 95% confident that the increase in Test4 score for every 1-point increase in Test3 score falls between .15 and 47, holding Test1 and Test2 fixed. O We are 95% confident that the Test3 is a useful linear predictor of Test4 score, holding Test1 and Test2 fixed. O We are 95% confident that the estimated slope for the Test4-Test3 line falls between .15 and .47 holding Test1 and Test2 fixed. O At a = .05, there is insufficient evidence to reject Ho: 83 = 0 in favor of Ha: B3 # 0. 0.0986 0.08os 0.3762 3.82 0.3265 4.04
Correlation
Correlation defines a relationship between two independent variables. It tells the degree to which variables move in relation to each other. When two sets of data are related to each other, there is a correlation between them.
Linear Correlation
A correlation is used to determine the relationships between numerical and categorical variables. In other words, it is an indicator of how things are connected to one another. The correlation analysis is the study of how variables are related.
Regression Analysis
Regression analysis is a statistical method in which it estimates the relationship between a dependent variable and one or more independent variable. In simple terms dependent variable is called as outcome variable and independent variable is called as predictors. Regression analysis is one of the methods to find the trends in data. The independent variable used in Regression analysis is named Predictor variable. It offers data of an associated dependent variable regarding a particular outcome.
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