Chisquared Monte Carlo integration

minagile

Hi, I have trouble to use this Monte Carlo integration method.

The question is " compute sample means for chi-squared distribution with degrees of freedom df=5. Using sample size of 10,50,100,500,1000,5000,10000"

I known rchisq(10,df=5) is the command to generate a random sample size 10 from a chisquare distribution with df=5.

Here is the command my lecture gave:
Step 1: Generate a large sample from relevant distribution
e.g. unifrv100_runif(n=100, min=0, max=1)

Step 2: Compute sample moment
muMC_ mean(unifrv100) [0.528, mu is ]
varMC_var(unifrv100) [0.084, var^2 is 0.083]

when I try to type it into R, I got "Error: could not find function "unifrv100_runif"

I don't really understand those command my lecture gave, is anyone could explain, or give me a hint. Thank you!!!

bnt

Looks to me like something got mangled in translation: I think the underscores should be "<-" variable assignments, and the bits in square brackets are comments, not commands. So unifrv100 is not a command, it's a variable name. These commands work:

unifrv100 <- runif(n=100, min=0, max=1)
muMC <- mean(unifrv100)
varMC <- var(unifrv100)

Note that these return nothing on screen: if you want to see the results, you have to just enter the variable name e.g.

> muMC
[1] 0.4947008
> varMC
[1] 0.08191964

(Your results will vary.)