CODEWITHSUNDEEP
ranova
user3170629
user3170629

Reputation: 499

Error messaging when running anova

I am currently receiving this error message from the following data set when I run the anova function: summary(aov(Site~Chlo,data=alldata)). The data set is saved under a txt file.

Error in levels(x)[x] : only 0's may be mixed with negative subscripts

In addition: Warning messages:

1: In model.response(mf, "numeric") :
  using type = "numeric" with a factor response will be ignored

2: In Ops.factor(y, z$residuals) : - not meaningful for factors

Year    Site    Chlo    DAC PARD    SST
2003    Seych   2.95    0.24    -39.36  0.40
2003    Brazil  -2.35   -0.14   22.97   4.03
2003    Indo    0.42    0.04    6.82    0.60
2004    Seych   0.20    0.02    -2.30   -0.63
2004    Brazil  -0.22   -0.01   -10.28  -1.22
2004    Indo    0.32    0.03    15.82   -1.72

Is there a reason behind this?

Upvotes: 0

Views: 5280

Answers (1)

Roland
Roland

Reputation: 132706

I assume you want test whether Chlo is different between Sites. So Chlo belongs on the LHS and Site on the RHS in the formula. With your data:

DF <- read.table(text="Year    Site    Chlo    DAC PARD    SST
2003    Seych   2.95    0.24    -39.36  0.40
2003    Brazil  -2.35   -0.14   22.97   4.03
2003    Indo    0.42    0.04    6.82    0.60
2004    Seych   0.20    0.02    -2.30   -0.63
2004    Brazil  -0.22   -0.01   -10.28  -1.22
2004    Indo    0.32    0.03    15.82   -1.72", header=TRUE)

summary(aov(Chlo~Site, data=DF))
#           Df Sum Sq Mean Sq F value Pr(>F)
#Site         2  8.247   4.124   2.043  0.275
#Residuals    3  6.055   2.018

So, it's not significantly different, but if n is that small there isn't much power and conducting an ANOVA doesn't really make sense.

Upvotes: 1

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