###########Example 1.2 from Lavine's book################# #Set number of MC replications N=1000 #make a vector of length N, filled with 0's wins=rep(0, N) #simulate a Come-out roll and if shooter wins on Come-out, #set wins=1 for( i in 1:N) { d <- sample( 1:6, 2, replace=T) if(sum(d)==7 || sum(d)==11 ) wins[i]=1 } #print the proportion of wins sum(wins)/N #print true probability: 2/9 #Execute the above as an R function: prob.win=function(N=1000){ wins=rep(0, N) for(i in 1:N){ d <- sample( 1:6, 2, replace=T) if(sum(d)==7 || sum(d)==11 ) wins[i]=1 } cat(c("true prob=",round(2/9,4)),fill=T) cat(c("empirical prob=",round(mean(wins),4),"[using", N, "replications]"),fill=T) } prob.win(N=100) prob.win(N=100) prob.win(N=1000) prob.win(N=1000) prob.win(N=10000) prob.win(N=10000) prob.win(N=100000) prob.win(N=100000) #Compute the probability of loss: prob.loss=function(N=1000){ loss=rep(0,N) for(i in 1:N){ d <- sample( 1:6, 2, replace=T) if(sum(d)==2 || sum(d)==3 || sum(d)==12 ) loss[i]=1 } cat(c("true prob=",round(1/9,4)),fill=T) cat(c("empirical prob=",round(mean(loss),4),"[using", N, "replications]"),fill=T) } prob.loss(N=100) prob.loss(N=100) prob.loss(N=1000) prob.loss(N=1000) prob.loss(N=10000) prob.loss(N=10000) prob.loss(N=100000) prob.loss(N=100000