a)Explain why it is necessary to examine the residuals. b) When blocking is used, discuss how the blocks are likely to be selected and whether their selection method has an impact on the analysis of variance procedure.
a)Explain why it is necessary to examine the residuals.
b) When blocking is used, discuss how the blocks are likely to be selected and whether their selection method has an impact on the analysis of variance procedure.
a) Examining the residuals i.e. residual analysis is a useful class of techniques for the evaluation of the goodness of a fitted model. Checking the underlying assumptions is important since most linear regression estimators require a correctly specified regression function and independent and identically distributed errors to be consistent. For a given data, the examination of the residuals of the fitted model is a standard tool for checking whether or not the underlying model assumptions hold. If the residuals in the regression model satisfies the OLS assumptions, then the model is considered valid. Since the statistical tests for significance are also based on these assumptions, the conclusions resulting from these significance tests are called into question if the assumptions regarding residuals are not satisfied.
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