# Binomial Random number Generation in R

We will learn here how to generate Bernoulli or Binomial distribution in R with example of flip of a coin. This tutorial is based on how to generate random numbers according to different statistical distributions in R. Our focus is in binomial random number generation in R.

We know that in Bernoulli distribution, either something will happen or not such as coin flip has to outcomes head or tail (either head will occur or head will not occur i.e. tail will occur). For unbiased coin there will be 50%  chances that head or tail will occur in the long run. To generate a random number that are binomial in R, use rbinom(n, size,prob) command.

rbinom(n, size, prob) command has three parameters, namely

where
n is number of observations
size is number of trials (it may be zero or more)
prob is probability of success on each trial for example 1/2

Some Examples

• One coin is tossed 10 times with probability of success=0.5
coin will be fair (unbiased coin as p=1/2)
>rbinom(n=10, size=1, prob=1/2)
OUTPUT: 1 1 0 0 1 1 1 1 0 1
• Two coins are tossed 10 times with probability of success=0.5
• > rbinom(n=10, size=2, prob=1/2)
OUTPUT: 2 1 2 1 2 0 1 0 0 1
• One coin is tossed one hundred thousand times with probability of success=0.5
> rbinom(n=100,000, size=1, prob=1/2)
• store simulation results in $x$ vector
> x<- rbinom(n=100,000, size=5, prob=1/2)
count 1’s in x vector
> sum(x)
find the frequency distribution
> table(x)
creates a frequency distribution table with frequency
> t=(table(x)/n *100)}
plot frequency distribution table
>plot(table(x),ylab=”Probability”,main=”size=5,prob=0.5″)

View Video tutorial on rbinom command

Updated: Apr 1, 2014 — 11:26 am