I have exported a CSV file from my EXCEL worksheet and its last column contained decimal values:

Subject;Group;Side;Difference;PercentError
M3;1;1;;
M5;1;1;375;18,75
M8;1;1;250;14,58
M10;1;1;500;12,50
M12;1;1;375;25,00
.
.
.


When I tried to do ANOVA test on it, R complained by givin error:

> Anova3LongAuditoryFemaleError.data <- read.csv("C:\\Documents\ and\ Settings\\Administrator\\My Documents\\CogSci\\tez\\Anova3LongAuditoryFemaleError.csv", header = TRUE, sep = ";")

> Anova3LongAuditoryFemaleError.aov = aov(PercentError ~ (Group * Side), data = Anova3LongAuditoryFemaleError.data)

Error in `storage.mode<-`(`*tmp*`, value = "double") : 
        invalid to change the storage mode of a factor
In addition: Warning message:
using type="numeric" with a factor response will be ignored in: model.response(mf, "numeric")

What must I do in order to make the ANOVA test on these fractional data?

Regards.

--
Emre Sevinc

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