tailieunhanh - Business process improvement_14

Tham khảo tài liệu 'business process improvement_14', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . Motivation Why is the 1 2 in the Model of the factor 2 effect B2 remains the same regardless of what other factors are included in the model. The net effect of the above two properties is that a factor effect can be computed once and that value will hold for any linear model involving that term regardless of how simple or complicated the model is provided that the design is orthogonal. This process greatly simplifies the model-building process because the need to recalculate all of the model coefficients for each new model is eliminated. Why is 1 2 the appropriate multiplicative term in these orthogonal models Given the computational simplicity of orthogonal designs why then is 1 2 the appropriate multiplicative constant Why not 1 3 1 4 etc. To answer this we revisit our specified desire that when we view the final fitted model and look at the coefficient associated with X2 say we want the value of the coefficient B2 to reflect identically the expected total change AY in the response Y as we proceed from the - setting of X2 to the setting of X2 that is we would like the estimated coefficient B2 to be identical to the estimated effect E2 for factor X2 . Thus in glancing at the final model with this form the coefficients B of the model will immediately reflect not only the relative importance of the coefficients but will also reflect absolutely the effect of the associated term main effect or interaction on the response. In general the least squares estimate of a coefficient in a linear model will yield a coefficient that is essentially a slope AY AX change in response change in factor levels associated with a given factor X. Thus in order to achieve the desired interpretation of the coefficients B as being the raw change in the Y ạY we must account for and remove the change in X X . What is the AX In our design descriptions we have chosen the notation of Box Hunter and Hunter 1978 and set each coded factor to levels of - and . This - and is a shorthand .