0
$\begingroup$

The motivation for my question is modelling changes in abundance of a species whose population is estimated from survey data. The challenge for me would be to see if ignoring a food indicator masks any population trend. Especially because I won't have every day surveyed in reality. There are two aspects I want to capture:

  1. the abundance should change over the year with a summer peak due to a breeding season.
  2. the abundance should also change with an indicator variable that shows whether the animals were clumped due to the presence of food or not.

What I have so far gets at the second point but not the first:

library(tidyverse)

set.seed(123)
day <- c(1:365) # day of the year
precount <- rpois(365, 5) # basic counts when there's no food
indicator <- sample(0:1, 365, replace = TRUE) # presence or absence of food
extra <- rpois(365, 20) # additional number of individuals in the presence of food


df <- data.frame(cbind(day, precount, indicator, extra)) # group it together 
df <- df %>% mutate(count = if_else(indicator == 1, precount + extra, precount)) %>% 
  select(day,count,indicator)
head(df)
df[sample(nrow(df), 20), ] %>% arrange(day) # pick some random days
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.