1. Emma is performing an experiment that requires individual handling of
some animals. The sizes of the animals are lognormally distributed: The natural
logarithms of their sizes has a normal distribution with mean 3 and standard
deviation 0.4. The time (in minutes) it takes to handle each animal is given by
10 + s · 1.5 + eε for animals with s ⤠20 20 + s · 0.8 + eε for animals
with s > 20
where ε is a random variable that is normally distributed with expectation 1
and variance 0.3.
For a randomly picked animal, what is the (approximate) probability that it can
be handled in less than 30 minutes?
We can solve this exercise using simulation, as follows: Simulate a vector S
with the sizes of 10000 animals, by using the rnorm function and the âexpâ
function. Then, compute a vector Time of length 10000 with the times it takes
to handle each of these 10000 animals: Remember that to separate between the
two cases, you can use notation like for example âTime[S < 20]â. The random
component eε can be added by combining the âexpâ function with the
ârnormâ function. Finally, you can find the proportion of simulated values
below 30. Re-do the computations a couple of times to get an idea of the
variability of the result.
s <- c(10000)
S <- exp(rnorm(s, 3, 0.4)) [1]# vector 10000, mean, sd
Time <- 10+S*1.5 [1] # 10 + s · 1.5 + eε for animals with s ⤠20
time <- 20+S*0.8 [1] # 20 + s · 0.8 + eε for animals with s > 20
can't get any further and i can't really find a good help page to solve the
code.
can you help me?
Lotta
------------------------------------------------------------------------------------
Eva-Lotta Blom PhD student
Dept. of BioEnv . Tjärnö
University of Gothenburg
452 96 Strömstad
Sweden
[[alternative HTML version deleted]]
______________________________________________
[email protected] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
