[R] questions about anova

Carlos Henrique Grohmann guano at usp.br
Sat Feb 28 20:54:29 CET 2004


Hello all,

I have two questions about anova (one is probably VERY basic...)

1 - when one asks for a summary of a trend surface created with surf.ls, he/she
gets:

> summary(g3r)
Analysis of Variance Table
 Model: surf.ls(np = 3, x = gradiente$east, y = gradiente$north, z =
gradiente$num1)
             Sum Sq    Df      Mean Sq  F value     Pr(>F)
Regression 215.7182     9 23.968693976 2686.508 < 2.22e-16
Deviation  480.1218 53814  0.008921876
Total      695.8401 53823
Multiple R-Squared: 0.31,       Adjusted R-squared: 0.3099
AIC: (df = 53814) -146390.9
Fitted:
     Min       1Q   Median       3Q      Max
0.007852 0.075619 0.100498 0.139042 0.338186
Residuals:
     Min       1Q   Median       3Q      Max
-0.29758 -0.04418 -0.01411  0.02536  0.51484
>

So, what's the meaning of the "Pr(>F)?



2 - I have six trend surfaces, and I like to make a anova for the significance
of increasing the degree of polynomial (like in Davis, 1986, p.422, Statistics
and data analysis in geology).

is there a way I can do it automatically or should I do it manually?


Thanks all.


-- 
+-------------------------------------------------+
        Carlos Henrique Grohmann - Guano  
    Geologist - MSc Student at IGc-USP - Brazil
       Linux User #89721  ICQ: 214752832
+-------------------------------------------------+




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