fishmethods (version 1.10-2)

remp: Random Number Generation from an Empirical Distribution

Description

Generates random numbers from a distribution created with empirical data

Usage

remp(n,obs=NULL)

Arguments

n

number of random observations to generate.

obs

vector of empirical observations.

Value

random observation(s)

Details

An empirical probability distribution is formed from empirical data with each observation having 1/T probabililty of selection, where T is the number of data points. The cumulative distribution function (cdf) is then created so that cumulative probability of the smallest observation = 0 and the largest observation = 1. Random values are generated by applying the probability integral transform to the empirical cdf using uniformly distributed random variable (U) on the interval[0,1]. If U corresponds directly to the cdf probability of a particular empirical observation, then the actual observation is selected. If U falls between cdf probabilities of empirical observations, then an observation is obtained by linear interpolation.

Examples

# NOT RUN {
# Striped bass recruits per spawning stock biomass ratios 
# for 2001-2011 from 2013 assessment
ratios<-c(799.22,794.78,969.81,1038.80,1101.45,1117.46,1126.16,
          1647.51,1882.30,1966.13,2189.25)
 # Select new recruits per SSB ratio for projection
 remp(1,ratios)
# }