Dear SAS Community,
I am using a polynomial regression since the relationship between the outcome var DTR (continuous) and Harvest month (categorical) appears to be curvilinear. I would like to predict DTR (days to ripe) when the fruits were harvested in Jan (1) and Feb (2). Since I am not sure if my estimates are correct, I would greatly appreciate your feedback. I have seven harvest months in total (1,2,3,4,5,6,8).
ods graphics on; proc glm data=one; Where Wks<6; class Harvest; model DTR= Harvest Harvest*Harvest/solution alpha=.05 clparm; estimate "pred DTR when Harvest=1" intercept 1 Harvest 1 0 0 0 0 0 0; estimate "pred DTR when Harvest=2" intercept 1 Harvest 0 1 0 0 0 0 0;
run; ods graphics off;
The GLM Procedure
Dependent Variable: DTR
Source
DF
Sum of Squares
Mean Square
F Value
Pr > F
Model
6
2061.513304
343.585551
47.34
<.0001
Error
554
4020.971545
7.258071
Corrected Total
560
6082.484848
R-Square
Coeff Var
Root MSE
DTR Mean
0.338926
35.00184
2.694081
7.696970
Source
DF
Type I SS
Mean Square
F Value
Pr > F
Harvest
6
2061.513304
343.585551
47.34
<.0001
Source
DF
Type III SS
Mean Square
F Value
Pr > F
Harvest
6
2061.513304
343.585551
47.34
<.0001
Parameter
Estimate
Standard Error
t Value
Pr > |t|
95% Confidence Limits
pred DTR when Harvest=1
10.8666667
0.24593480
44.19
<.0001
10.3835879
11.3497454
pred DTR when Harvest=2
8.8292683
0.42074473
20.98
<.0001
8.0028182
9.6557184
Parameter
Estimate
Standard Error
t Value
Pr > |t|
95% Confidence Limits
Intercept
7.625000000
B
0.24593480
31.00
<.0001
7.141921263
8.108078737
Harvest 1
3.241666667
B
0.34780434
9.32
<.0001
2.558490165
3.924843169
Harvest 2
1.204268293
B
0.48735004
2.47
0.0138
0.246988411
2.161548175
Harvest 3
-0.075000000
B
0.49186961
-0.15
0.8789
-1.041157474
0.891157474
Harvest 4
-1.200000000
B
0.38885707
-3.09
0.0021
-1.963814549
-0.436185451
Harvest 5
-0.725000000
B
0.49186961
-1.47
0.1411
-1.691157474
0.241157474
Harvest 6
-2.250000000
B
0.34780434
-6.47
<.0001
-2.933176502
-1.566823498
Harvest 8
0.000000000
B
.
.
.
.
.
Note:
The X'X matrix has been found to be singular, and a generalized inverse was used to solve the normal equations. Terms whose estimates are followed by the letter 'B' are not uniquely estimable.
Thank you very much!
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