Question 1. True or False Questions (20 points) For the following statements cir

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Question 1. True or False Questions (20 points) For the following statements circle (T)rue or (F)alse. You don't have to explain. T F T F T F The residuals satisfy ie 0 An indication of multicollinearity is a small overall F statistic but large t statistics. The effect of an observation on the regression line is determined only by its y value. with each explanatory variable added to the model. T F When multicollinearity is present, it affects the regression coefficient estimates but does not T F For multiple regression, a larger R? means that the model is more useful in terms of estimation T F The fact, that an observation has been classified as unusual based on the DFITS or Cook's affect the ability to obtain a good fit of the regression. and prediction. D statistic, means that this observation is useless and should be deleted from the analysis. T F + ?,a + ?2z? + ?. Once a decision is rnade to keep Consider the second-order model y = the second-order term in the model, the lower-order term z is typically kept in the model regardless of the t test result on its coefficient (B1). TFThe cone-shaped pattern in the residual plot indicates a violation of the constant variance assumption

Explanation / Answer

1. TRUE .None of the t-ratios for the individual coefficients is statistically significant, yet the overall F statistic is significant.

2.FALSE. The effect of a particular observation depends on the slope coefficient as well.

3.TRUE. The sum of the residuals of a regression model is 0. The sum of all deviations (where each deviation is defined as ei=xi?x¯) to the right of the mean value are equal to the sum of all the deviations to the left of that mean.

4. TRUE. R squared is the proportion of the outcome variance that can be explained by the explanatory variables. The more variables you include the more variance can be explained by the model.

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