Hi All,

I have a question about plotting a one-to-one line and x-and-y error bars on a scatterplot for my data. I just can't seem to work it out!


I have data from an experiment with 7 different treatment levels with 3 replicates, that is set-out as follows:

Treatment Level    Replicate    Reponse-weight    Covariate-weight
1                            1                0.945                    0.232
1                            2                0.345                    0.213
1                            3                0.945                    0.341

2                            1                0.925                    0.122
2                            2                0.115                    0.110
2                            3                1.20                      0.27

... and so on..... for the 7 different treatment levels (21 rows altogether)


I need to plot the means of each different treatment level on a scatterplot (Response-weight on y-axis and Covariate-weight on x-axis). I then need a one-to-one line added to the plot and x and y error bars. I have read the code for x-and-y error bars in Crawley's R book where he creates a function to apply the error bars - unfortunately, I can not understand how to adapt it to my dataset so I'm hoping someone would advise me of the simplest way to do this.

So my questions are:
1) How do I plot x-and-y error bars to my scatterplot of the above data?
2) How do I add a one-to-one line?


Thank you - please let me know if I should provide anymore information.


Sarah






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