I have limited information with which to compare two means, is it still possible in R?
We have a group of students (1,000 students) about whom we have mean and standard deviation information, and we did an experiment on a sub-set of them (again we have mean and standard deviation on this subset). I do not, however, have data on the individual students.
All Students (SD), Experiment Students (SD)
Age 14 (.5), 15.5 (1)
Caucasian 22%, 35%
African American 41%, 39%
Is there a command to compare, as a t-test, the two means when the only information I have is the mean, standard deviation, and sample size? My understanding from R is that t.test(a, mu) looks at all 'a' values for observations in a column of a dataframe, it does not expect a mean value to be input. I get an error when it tried.
Further, how does R cope with variables that are not means but percentages, for example the race/ethnicity data?