[R] Best method for comparing rectangles sections of beach

Jhope jeanwaijang at gmail.com
Mon Oct 8 12:02:17 CEST 2012


Hi R-listers, 

I am trying to compare sections of the beach separated from the HTL to the
Veg (east to west), separated into indices (-5 to 30m), HTLIndex.  Cross
parallel (north to south) are major beach sections (Rayos 1, 2, 3, 4 and
MNB). I am thinking to do an ANOVA for each independent rectangle of beach
(not exactly but will be treated as). The HTL from (0-5m) in Rayo 1 is one
rectangle of beach; (0-5m) in Rayo 2 is another... etc.

I was considering an 2-way anova with interactions - see below. But this
does not identify each section of the beach by 5 meters and Rayos.  

1) What is the best way to compare these beach rectangle sections? 
2) Each Rayo is a little bit different in size but for management purposes,
it is identified by these sections (leave alone or use), so maybe ANOVA is
appropriate? 
3) Script suggestions greatly appreciated. 

Please advise, Jean

head() included below
----------------

summary(aov(HSuccess ~ HTLIndex*Aeventexhumed, data=data.to.analyze))

                       Df Sum Sq Mean Sq F value  Pr(>F)   
HTLIndex                6  0.691 0.11524   3.023 0.00937 **
Aeventexhumed           2  0.106 0.05308   1.393 0.25329   
HTLIndex:Aeventexhumed 11  0.376 0.03418   0.897 0.54645   
Residuals              98  3.736 0.03812                   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 
5 observations deleted due to missingness
Warning message:
In model.matrix.default(mt, mf, contrasts) :
  variable 'Aeventexhumed' converted to a factor

---------
> head(data.to.analyze)
  QuadratEvent        ExDate Sector Quadrat Aeventexhumed ST0 ST1 ST2 ST3
ST4 Shells
1         8.1A Nov. 26, 2010     14       8             A   6   0   1  98  
1     72
2        10.1A Nov. 26, 2010     13      10             A   4   0   0 109  
1     74
3        14.1A Nov. 18, 2010     20      14             A   6   0   2  26 
11    106
4        19.1A Nov. 22, 2010     79      19             A   0   0   0   0  
0    102
5        23.1A Nov. 20, 2010     34      23             A 135  23   1   6  
0    125
6        24.1A Nov. 28, 2010     34      24             A 660   0   2   0  
0      4
  Hatchlings MaxHatch DeadHatch Oldeggs TotalEggs QuadratID Sector
Aeventexhumed   Veg
1          3       72         2       0       178       8.1     14            
A  9.75
2          4       74         0      21       188      10.1     13            
A 16.34
3          1      106         1     165       151      14.1     20            
A  3.15
4          1      102         0       0       102      19.1     79            
A  5.70
5         48      125         0       0       290      23.1     34            
A 12.20
6          0        4         0      36       666      24.1     34            
A  4.82
  Berm   HTL Estuary   Rayos NotHatched DevelopIndex VegIndex  HTLIndex
1   NA  4.66      NA Rayos.1        106     3.865169   (6-10)     (0-5)
2   NA -2.47      NA Rayos.1        114     4.920213  (16-20) (-5-(-1))
3   NA 16.00      NA Rayos.2         45     5.622517    (0-5)   (16-20)
4   NA    NA    11.8 Rayos.2          0     1.000000   (6-10)      <NA>
5   NA  2.35      NA Rayos.3        165     3.406897  (11-15)     (0-5)
6   NA 22.85      NA Rayos.3        662     5.981982    (0-5)   (21-25)



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