I have 7 different data points for virus concentration collected at 3 different time points. How do I graph this with error bars in R?

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I would suggest you next approach. If you want error bars you can compute it based on mean and standard deviation. In the next code is sketched the way to do that. I have used one standard deviation but you can set any other value. Also as you want to see different samples, I have used facet_wrap(). Here the code:

library(ggplot2)
library(dplyr)
#Data
df <- data.frame(sample=c(rep('24 hour',3),rep('48 hour',2),rep('72 hour',2)),
                 titer=c(667, 1330, 1670,323000, 590000,3430000, 4670000),
                 stringsAsFactors = F)
#Compute error bars
df <- df %>% group_by(sample) %>% mutate(Mean=mean(titer),SD=sd(titer))
#Plot
ggplot(df,aes(x=sample,y=titer,color=sample,group=sample))+
  geom_errorbar(aes(ymin=Mean-SD,ymax=Mean+SD),color="black")+
  geom_point()+
  scale_y_continuous(labels = scales::comma)+
  facet_wrap(.~sample,scales="free")

Output:

enter image description here

If you have a common y-axis scale, you can try this:

#Plot 2
ggplot(df,aes(x=sample,y=titer,color=sample,group=sample))+
  geom_errorbar(aes(ymin=Mean-SD,ymax=Mean+SD),color="black")+
  geom_point()+
  scale_y_continuous(labels = scales::comma)+
  facet_wrap(.~sample,scales="free_x")

Output:

enter image description here

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