Problems with Anova

417 views Asked by At

I have some issues trying to conduct an Anova for a repeated survey.

This is my data basis: 40 participants from 3 school classes and I wanted to know how motivated the pupils were for learning a certain subject at two different points of time.

Now I wanted to conduct an ANOVA in order to find out whether there are significant differences in the motivation of these three groups (i.e. classes). However, I cannot seem to figure it out.

I've tried the following:

> anova.rm <- ezANOVA(daten.long, dv=.(motivation),
+ wid=.(id), within=.(time) )

Warnung: "time" will be treated as numeric. 
Warnung: There is at least one numeric within variable, therefore aov() will be used for computation and no assumption checks will be obtained.
> anova.rm
$ANOVA
     Effect DFn DFd        F         p p<.05       ges
1 time   1   2 3.887892 0.1873993       0.6603199

--> In this one-factored analysis the motivation is already related to the class, but it doesn't give me any information whether there are any differences between the groups if I do a post hoc-test (such as Fishers Least Significance Difference or the pairwise.t.test)

Therefore, I've tried to use the multifactorial variance analysis:

> anova.mixed <- ezANOVA(daten.long, dv=.(motivation), wid=.(id), within=.(time), between=.(class))

Warnung: "time" will be treated as numeric.
Warnung: "class" will be treated as numeric.
Warnung: There is at least one numeric within variable, therefore aov() will be used for computation and no assumption checks will be obtained.
> anova.mixed

$ANOVA
            Effect DFn DFd           F         p p<.05        ges

1           class   1   1  0.05304433 0.8558908       0.04881692

2           time    1   1 16.05556143 0.1556988       0.34263494

3      class:time   1   1  7.25926249 0.2262510       0.19071808

Same problem for this try. I have no idea whether I'm on the right track to get to the point if there are any significant differences between my groups at the two points of time.

I'm thankful for your help and advice! :)

0

There are 0 answers