This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: 5E Final practice Formulas at end are as they will be on exam. For any hypothesis test, clearly state null and alternative hypotheses. 1. Suppose two variables x and y have a negative correlation and follow the regression model y = 2 . 1 x + , where is normal with a standard deviation of .7. We do a leastsquares regression using 30 values for x , where the values have a mean of 4 and a sample standard deviation of 1.2. What is the probability that we get a positive slope in our regression analysis? What if we use 100 values for x , with the same mean and standard deviation them? What if the standard deviation of is only .4? Hint: Use 12.17 from p. 513. To do that use the sample st dev to find ∑ ( x i ¯ x ) 2 . 2. Below is a scatter plot of data with regression output: b = 5 . 1, b 1 = 4 . 7 and SSE = 345. The sample standard deviation of the x values are 12.3 and the mean is 5.5. The sample standard deviation of the y values are 3.4 and the mean is 10.1. There are 30 data points plotted. Find a 95% confindence interval for the the slope b 1 . At a 5% significance level, does the data provide evidence that there is a correlation between the variables? Find a 95% confidence interval for the mean of y given that x is equal to 7. Find a 95% confidence interval for an individual valueequal to 7....
View
Full Document
 Fall '08
 EduardoMontoya
 Statistics, Least Squares, Regression Analysis, Standard Deviation, Errors and residuals in statistics

Click to edit the document details