R T. Test Group By
I Have Stumbled Across a Bit of an Annoying Problem. I Am Trying to Perform Multiple Independent Sample T-Tests at Once, Grouped by a Value. to Put It into an...
I have stumbled across a bit of an annoying problem. I am trying to perform multiple independent sample t-tests at once, grouped by a value.
To put it into an example: In 5 cities we have measured job satisfaction between males and females. For every subject we know their city, their gender, and their satisfaction score. We can do a t-test over the whole sample like this:
t.test(Score ~ Gender, paired = FALSE)
However, I want to perform a t-test for each city, to see if there is a difference in the average job satisfaction per gender per city. How do I do this?
1 Answer
You can use lapply with split to do a group by t.test,
lapply(split(mtcars, factor(mtcars$cyl)), function(x)t.test(data=x, mpg ~ am, paired=FALSE))
Here I have used mtcars data, and performed a independent t.test by using cyl as group to perform a t.test on mpg(continuous data) and am (categorical data). Let me know if this is not you are expecting.
Robert Thorne covers electric vehicle innovations, autonomous driving systems, global mobility trends, and automotive engineering developments.
