What do additional arguments indicate in the simple.sim function in R?

Question

In R suppose that we have the following code:

 require("UsingR") # required for "simple.sim" function below
 f= function(n=100,mu=0,sigma=1) {
     nos = rnorm(n,mu,sigma)
     (mean(nos)-mu)/(sigma/sqrt(n))
    }

    simulations = simple.sim(100,f,100,5,5)
    hist(simulations,breaks=10,prob=TRUE)

Does this basically simulate 100 normal random variables with mean 5 and standard deviation 5? In the simulations argument, what do the 5's indicate?

Answer 1

When you look at the simple.sim() help page you see there are two arguments and an ellipsis("..."). The ellipsis allows you to pass any unspecified argument through simple.sim() into one of the nested functions, here f() and rnorm(). So you are getting mu is 5 and sigma is 5. It is pretty bad practice to pass unnamed arguments this way, so be careful!

Now you know where the numbers are being passed. Do you think the output of your f function is norm(mean=5,sd=5)?

f() creates a vector of random normals with mean mu=5 and standard deviation sigma=5 but then it applies a function. The results of that function may or may not be normal.