1、發酵豬飼料的應用研究飼料發酵后的酸度是評價飼料合格與否的一個重要指標，它受多個因素的影響，其中發酵溫度、發酵時間、pH值和投曲度對其影響顯著。本文利用16次發酵豬飼料試驗數據和結果，采用逐步回歸分析法選擇適當的二次多項式，以預測酸度值。逐步回歸分析法程序如下：(x1-x4分別代表發酵溫度、發酵時間、pH值和投曲度，y代表飼料酸度)data e11;input x1-x4 y;cards;10 12 7 5 6.3610 24 6 10 7.4310 48 5 10 10.3 10 72 4 5 11.5620 12 6 10 8.6620 24 7 5 5.3920 48 4 5 15.520

2、 72 5 10 19.5330 12 5 5 12.0830 24 4 10 13.1330 48 7 10 8.0330 72 6 5 12.4550 12 4 10 13.4950 24 5 5 10.7750 48 6 5 9.850 72 7 10 16 64;proc print;run;proc reg data=e11;model y=x1-x4/selection=stepwise;run;運行結果如下：The SAS System 14:27 Saturday, December 17, 2008 1 Obs x1 x2 x3 x4 1 10 12 7 5 6.362 10

3、 24 6 10 7.433 10 48 5 10 10.304 10 72 4 5 11.565 20 12 6 10 8.666 20 24 7 5 5.397 20 48 4 5 15.508 20 72 5 10 19.539 30 12 5 5 12.0810 30 24 4 10 13.1311 30 48 7 10 8.0312 30 72 6 5 12.4513 50 12 4 10 13.4914 50 24 5 5 10.7715 50 48 6 5 9.8016 50 72 7 10 16.00The SAS System 14:27 Saturday, December

4、 17, 2008 2The REG ProcedureModel: MODEL1Dependent Variable: yStepwise Selection: Step 1Variable x2 Entered: R-Square = 0.2790 and C(p) = 12.8179Analysis of VarianceSum of MeanSource DF Squares Square F Value Pr > FModel 1 59.46090 59.46090 5.42 0.0354Error 14 153.64110 10.97436Corrected Total 15

5、 213.10200Parameter StandardVariable Estimate Error Type II SS F Value Pr > FIntercept 8.01733 1.62806 266.13177 24.25 0.0002x2 0.08366 0.03594 59.46090 5.42 0.0354Bounds on condition number: 1, 1-Stepwise Selection: Step 2Variable x3 Entered: R-Square = 0.5506 and C(p) = 5.4704The SAS System 14:

6、27 Saturday, December 17, 2008 3The REG ProcedureModel: MODEL1Dependent Variable: yStepwise Selection: Step 2Analysis of VarianceSum of MeanSource DF Squares Square F Value Pr > FModel 2 117.32892 58.66446 7.96 0.0055Error 13 95.77308 7.36716Corrected Total 15 213.10200Parameter StandardVariable

7、Estimate Error Type II SS F Value Pr > FIntercept 17.37283 3.59474 172.07005 23.36 0.0003x2 0.08366 0.02945 59.46090 8.07 0.0139x3 -1.70100 0.60693 57.86802 7.85 0.0150Bounds on condition number: 1, 4-Stepwise Selection: Step 3Variable x1 Entered: R-Square = 0.6334 and C(p) = 4.6181Analysis of Va

8、rianceSum of MeanSource DF Squares Square F Value Pr > FModel 3 134.98662 44.99554 6.91 0.0059Error 12 78.11538 6.50962Corrected Total 15 213.10200The SAS System 14:27 Saturday, December 17, 2008 4The REG ProcedureModel: MODEL1Dependent Variable: yStepwise Selection: Step 3Parameter StandardVaria

9、ble Estimate Error Type II SS F Value Pr > FIntercept 15.41954 3.58114 120.68562 18.54 0.0010x1 0.07103 0.04313 17.65770 2.71 0.1255x2 0.08366 0.02768 59.46090 9.13 0.0106x3 -1.70100 0.57051 57.86802 8.89 0.0115Bounds on condition number: 1, 9-All variables left in the model are significant at the 0.1500 level.No other variable met the 0.1500 significance level for entry into the model.Summary of Stepwise SelectionVariable Variable Number Partial Model Entered Removed Vars In R-Square R-Square C(p) F value Pr>Fx2 1 0.2790 0.2790 12.8179 5.42 0