the LPI does not tell us the number of species, populations or individuals lost; the number of extinctions that have occurred; or even the share of species that are declining. It tells us that between 1970 and 2018, on average, there was a 69% decline in population size across the 31,821 studied populations.
The LPI indicates that vertebrate populations have decreased by almost 70% over the last 50 years. This is in striking contrast with current studies based on the same population time series data that show that increasing and decreasing populations are balanced on average. Here, we examine the methodological pipeline of calculating the LPI to search for the source of this discrepancy. We find that the calculation of the LPI is biased by several mathematical issues which impose an imbalance between detected increasing and decreasing trends and overestimate population declines.
Thanks for sharing both the original and this version of the argument!
I realize this is basically an aside and doesn’t really affect your bottom line, but I don’t think you can draw this inference:
Quoting Our World In Data:
This paper also argued the methodology is systematically biased downwards, but I haven’t evaluated it.