What kind of Diagram to visualize Results from Software Usability test? I know how to use R but I am kind of stuck on the statistical part here:
I need to visualize the results from a software usability test where the total number of clicks of each tester for every one of the three tasks they had to complete were recorded. The total time needed for each of the three tasks was also recorded.
I want only to visualize the results from 10 testers, so I was thinking about using a bar plot, but I can't think of any plot where I can put the click count as well as the time needed into one plot that makes sense.
I have the data in two .csv files (if that matters). 
Also do you think I should be aware of any caveats? such as should I normalize something?
Any help would be appreciated!
Martin
 A: Building on @AndyW's suggestion of a scatter plot as the obvious way of showing two continuous variables, and facets or colours as the obvious way to identify the different users and tasks, something like the following (ggplot or lattice graphics are admirable for this sort of thing).
You could add extra info to the plots - regression lines or average values - depending on exactly how your analysis proceeds from here.
test <- data.frame(
    user=factor(rep(1:10,3)),
    task=factor(rep(1:3, c(10,10,10))),
    clicks=rpois(30,10))
test$time <- test$clicks*rnorm(30,5,1) + rnorm(30,10,5)

library(ggplot2)

ggplot(test, aes(x=clicks, y=time, color=user)) +
    geom_point(size=2) +
    facet_wrap(~task) +
    scale_color_brewer(palette="Set3")+
    opts(title="Clicks and times, faceted by task")

ggplot(test, aes(x=clicks, y=time, color=task)) +
    geom_point(size=2) +
    facet_wrap(~user, ncol=5) +
    scale_color_brewer(palette="Set1") +
    opts(title="Clicks and times, faceted by user")



