# NetCDF questions and population density data

1. Is your grid on integers or centered? that is, e.g., should 118,34 cover the rectangle from 117.5-118.5 and 33.5-34.5 , or should it cover the rectangle from 118-119 and 34-35?

**The grid lies is on the degree integers, not centered.
**

2. There are 20 variables in my data. Unfortunately, they are named X1 through X20. Is there a description of what each variable contains?

**Please see the gpw_v4_netcdf_contents_rev11.csv file that was included in the .zip. Rows 62-81 explain the variable definitions.**

3. I can guess from the variables' properties that X13, X17, X18, and X20 are years. <https://sedac.ciesin.columbia.edu/data/set/gpw-v4-population-density-adjusted-to-2015-unwpp-country-totals-rev11> states it would go from 2000 to 2020. Alas, my variables do not seem to have years after 2016 in them.

**Those are years but read the definitions in the .csv described above. The population density data is in the first 5 variables.**

4. Is the population count vs the population density database just different in terms of making the area conversion easier?

**Yes, and because the data are in geographic coordinates the area of each
pixel is not the same, so we release both a count and density layer.
**