scanstatistic.R

## allocate 'events' events among 'times' times
## what is the maximum number in an interval of width 'scanwidth'?
## return table based on N replications
scanFixedTotal<-function(times, events, scanwidth,N){
	
	values<-replicate(N,{
		x<-numeric(times)
		for(i in sample(times,events)){
			x[i]<-x[i]+1
		}
		max(rowSums(embed(x,scanwidth)))
	}
	)
	table(values)
}

## simulate events at rate 'events/times' for 'times' times
## what is the maximum number in an interval of width 'scanwidth'?
## return table based on N replications
scanRandomTotal<-function(times, events, scanwidth,N){
	
	values<-replicate(N,{
		x<-rpois(times,events/times)
		max(rowSums(embed(x,scanwidth)))
	}
	)
	table(values)
}

##example: 91 fatal crashes involve 18+ people in 10 years
scanRandomTotal(3650,91,8,10000)
scanFixedTotal(3650,91,8,10000)