To whom it may concern:
 
I am trying a factorial design a system of mine that has two factors.
Each factor was set at four different levels, with one replication for
each of the combinations. My data is as follows:
 

           A           B                     Response

1        600        2.5                   0.0257

2        600        2.5                   0.0254

3        600        5                      0.0217

4        600        5                      0.0204

5        600        10                    0.0191

6        600        10                    0.0210

7        600        20                    0.0133

8        600        20                    0.0139

9        800        2.5                   0.0312

10       800       2.5                   0.0317

11       800       5                      0.0307

12       800      5                      0.0309

13       800       10                    0.0330

14       800       10                    0.0318

15       800       20                    0.0225

16       800       20                    0.0234

17      1000      2.5                   0.0350

18      1000      2.5                   0.0352

19      1000      5                      0.0373

20      1000      5                      0.0361

21      1000     10                    0.0432

22      1000     10                    0.0402

23      1000     20                    0.0297

24      1000     20                    0.0306

25      1200      2.5                   0.0324

26      1200      2.5                   0.0326

27      1200      5                      0.0353

28      1200      5                      0.0353

29      1200     10                    0.0453

30      1200     10                    0.0436

31      1200     20                    0.0348

32      1200     20                    0.0357

 

I am able to enter my data into R and obtain an ANOVA table (which I
have been able to verify as correct using an excel spreadsheet), using
the following syntax:

 

>Factorial<-data.frame(A=c(rep(c("600", "600", "600", "600", "800",
"800", "800", "800", "1000", "1000", "1000", "1000", "1200", "1200",
"1200", "1200"), each=2)), B=c(rep(c("2.5", "5", "10", "20", "2.5", "5",
"10", "20", "2.5", "5", "10", "20", "2.5", "5", "10", "20"), each=2)),
Response = c(0.0257, 0.0254, 0.0217, 0.0204, 0.0191, 0.021, 0.0133,
0.0139, 0.0312, 0.0317, 0.0307, 0.0309, 0.033, 0.0318, 0.0225, 0.0234,
0.035, 0.0352, 0.0373, 0.0361, 0.0432, 0.0402, 0.0297, 0.0306, 0.0324,
0.0326, 0.0353, 0.0353, 0.0453, 0.0436, 0.0348, 0.0357))

 

> anova(aov(Response~A*B, data=Factorial))

 

However, this is as far as I am able to go. I would like to obtain the
coefficients of my model, but am unable. I would also like to use other
non-linear models as these factors are not linear. Also would like to
add A^2 and B^2 into the ANOVA and modeling. 

 

Please can you help with regard and offer some advice. Your help is much
appreciated.

 

Yours sincerely,

Leslie Correia

------------------------------------------------

Department of Process Engineering

University of Stellenbosch

Private Bag X1

Matieland, 7602

Stellenbosch

Tel:   0837012017

E-mail: lcorreia@sun.ac.za <mailto:lcorreia@sun.ac.za> 

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