CODEWITHSUNDEEP
r
Tanjina Pial
Tanjina Pial

Reputation: 5

probability function for unfair dice

Given a fair four-sided die and let X denote the associated random variable. What is the probability distribution of X? What is the expectation of X?

#1

x <- 1:4 
sample_function <- sample (1:4, size=20,replace = TRUE, prob = NULL) 
sample_function <- sum(sample (1:4, size=20,replace = TRUE, prob = NULL))

#2

my.sample <- function(die1=1:4,  prob1=NULL,Nsample=20) {
      die <- sample(die1, prob=prob1, replace = TRUE, size = Nsample)
      return(die)
    }
my.sample()
    
my.sample(die1 = 1:4, prob1 = c(1/2 , 1/6,1/6, 1/6), Nsample = 20)

I do not understand how can I calculate the probability distribution of x and how can I use prob function for unfair dice.

Upvotes: 0

Views: 1130

Answers (1)

ThomasIsCoding
ThomasIsCoding

Reputation: 101848

As Roland mentioned, your Nsample should be sufficient large (otherwise the Monte Carlo simulation result would be rather biased). If you wants the empirical probability distribution, you can use prop.table + table like below

s <- prop.table(table(my.sample(die1 = 1:4, prob1 = c(1/2, 1/6,1/6, 1/6), Nsample = 1e8)))

which gives

> s

        1         2         3         4
0.4999951 0.1666763 0.1666949 0.1666338

Upvotes: 0

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