[R] Help With ANOVA (corrected please ignore last email)

[Amit Patel]

Sorry i had a misprint in the appendix code in the last email


Hi I needed some help with ANOVA

I have a problem with My ANOVA
analysis. I have a dataset with a known ANOVA p-value, however I can
not seem to re-create it in R.

I have created a list (zzzanova) which contains
1)Intensity Values
2)Group Number (6 Different Groups)
3)Sample Number (54 different samples)
this is created by the script in Appendix 1

I then conduct ANOVA with the command
> zzz.aov <- aov(Intensity ~ Group, data = zzzanova)

I get a p-value of
Pr(>F)1 
0.9483218 

The
expected p-value is 0.00490 so I feel I maybe using ANOVA incorrectly
or have put in a wrong formula. I am trying to do an ANOVA analysis
across all 6 Groups. Is there something wrong with my formula. But I think I
have made a mistake in the formula rather than anything else.




APPENDIX 1

datalist <- c(-4.60517, -4.60517, -4.60517, -4.60517, -4.60517, -4.60517, -4.60517, 3.003749, -4.60517, 
    2.045314, 2.482557, -4.60517, -4.60517, -4.60517, -4.60517, 1.592743, -4.60517,
    -4.60517, 0.91328, -4.60517, -4.60517, 1.827744, 2.457795, 0.355075, -4.60517, 2.39127,
    2.016987, 2.319903, 1.146683, -4.60517, -4.60517, -4.60517, 1.846162, -4.60517, 2.121427, 1.973118,
    -4.60517, 2.251568, -4.60517, 2.270724, 0.70338, 0.963816, -4.60517,  0.023703, -4.60517,
    2.043382, 1.070586, 2.768289, 1.085169, 0.959334, -0.02428, -4.60517, 1.371895, 1.533227)

"zzzanova" <-
structure(list(Intensity = datalist, 
Group = structure(c(1,1,1,1,1,1,1,1,1,
         2,2,2,2,2,2,2,2,
         3,3,3,3,3,3,3,3,3,
         4,4,4,4,4,4,4,4,4,4,
         5,5,5,5,5,5,5,5,5,
         6,6,6,6,6,6,6,6,6), .Label = c("Group1", "Group2", "Group3", "Group4", "Group5", "Group6"), class = "factor"), 
    Sample = structure(c( 1, 2, 3, 4, 5, 6, 7, 8, 9, 
    10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 
    20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 
    30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,41,42,43,44,45,46,47,48,49,50,51,52,53,54)
))
, .Names = c("Intensity", 
"Group", "Sample"), row.names = 
c("1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
"11", "12", "13", "14", "15", "16", "17", "18", "19", "20",
"21", "22", "23", "24", "25", "26", "27", "28", "29", "30",
"31", "32", "33", "34", "35", "36", "37", "38", "39", "40",
"41", "42", "43", "44", "45", "46", "47", "48", "49", "50",
"51", "52", "53", "54"),class = "data.frame")