j'utilise cette ligne de code mais je n'arrive pas a ajouter des bars d'erreur correspondant au ecart type

Hi, welcome to the forum.

I think you are missing some code.

See geom_errorbar function - RDocumentation.

To really check things we need some sample data.
A handy way to supply some sample data is the dput() function. In the case of a large dataset something like dput(head(mydata, 100)) should supply the data we need. Just do dput(mydata) where mydata is your data. Copy the output and paste it here.
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