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    1. In GPW data that is comprised of 2.5 arc min cells, are the cells georeferenced from the cell center, or right/left and upper/lower corner?  I understand that xllcorner and yllcorner give the starting lat/lon for overall grid position, but are the cell data themselves valued at each lower left corner?

    2. In GPWv3 Population Density Grid data, .ASCII format, what is the definition of "xllcorner" and "yllcorner" values?

    3. I plan to use the global population data. I would like to know what information is stored in the *.stx and *.blw files. Also is there a way to map the grids to (latitude, longitude) ?

    4. I am having difficulties locating the metadata for your population density data of the world, GPWv3. Is the metadata available online?

    5. I have downloaded India 1995 population data (GPW2). Why is there no variation in colours when I view the files in ArcView?

    6. I'm preparing an article about "human migration and environment". Do you have any data or information relevant to this topic (causes, effects, links)?

    7. Is there any way to find out how block groups from the 1990 census match with block groups from the 1980 census? I need to find or create data that would show the change in block group characteristics over time. I tried MABLE but it only has block group information for 1990 census.

    8. How big is the file (.ascii) of GRUMP data? I am downloading from a very fast connection and it is still taking a really long time.

    9. I am using the GPW data (version 3) for China and I have some problems with understanding the proportional allocation mechanism. The reason that I am asking is that there are so many zeroes and I can not understand how there can be any zero?

    10. I am attempting to download and use your 1990 Adjusted Population Numbers for Africa. I have successfully downloaded the zipped BIL file. In order to convert this for use in my GIS software (I am using IDRISI) I need to know information which I cannot find in any of the documentation files you have made accessible. Please can you answer the following questions regarding the BIL format: 1. Is there a header - if so what is its size? 2. What are the maximum and minimum grid co-ordinates for your Africa data? 3. Are the data 8-bit or 16-bit? 4. What reference system do you use, and what the reference units measured in?

    11. I downloaded your Population Grid maps for the United States and the World both at a resolution of 2.5 arc minutes, and I have a few questions. First, what are the units of the grid values? From what I've noticed, they run anywhere from the thousands to 1e-9, which seems kind of strange. Also, at the same resolution, why does the United States have more columns than the world?  The data at the top says there are 8688 columns at a cell size of 0.0416666, which would imply 362 longitudinal degrees of data.

    12. Where are the attribute tables for the GPWv3/GRUMP data? I would eventually like to extract statistics (such as population count) using features in another layer, but am not sure that I'll be able to do so given that there are no accompanying attribute tables. Could you advise as to how I should proceed?

    13. Where are the attribute tables for the GPWv3/GRUMP data? I would eventually like to extract statistics (such as population count) using features in another layer, but am not sure that I'll be able to do so given that there are no accompanying attribute tables. Could you advise as to how I should proceed?

    14. I would like to do a time series analysis to look at the change in environmental sustainability in specific countries, but I am unsure if the data for your 2001 and 2002 ESI is different, or whether the 2002 ESI is just the result of fine-tuning definitions and categories.

    15. In the China County-level Data on Provincial Economic Yearbooks, each of the DBF files has its meaning, such as 1990B1.dbf is about the General Survey. But when I open the file, all the item names are given as sequential number codes, such as B1990001, B1990002, B1990003. I want to know about each item's name -- what's the value meaning?

    16. I downloaded the GPWv3 Population Density .ascii format. I'm having trouble parsing this data correctly. I read in the meta data at the top of the file (lower-left latitude/longitude origin of the grid, cell size, etc) and these seem to make sense. But when I plot all cells with a density greater than 300, the points are not syncing up with the map (i.e. I'm seeing large blobs of population in the Pacific). Am I correct in assuming that the rows of the file begin at the lower-left point given, with the columns representing increasing longitude and rows representing increasing latitude?

    17. I would like to download GPW and GRUMP data, but I'd like to know if it is possible to download files by some coordinate extent, rather than by country?

    18. I downloaded the global level data file v2glp95ag.zip I looked into the file content on a unix system using 'more', and found most grid values to be less than 1. This is unexpected, as I expected the number of inhabitants per cell. What did I do wrong?

    19. Why was gROADS developed?

    20. What is the difference between "..ag"  and "...g" files?  For example, I've downloaded the population grid for the whole world for 1990, in "grid" format, and there are two sets of raster files.  When I open them in ArcGIS, they seem to show similar data, but the range of values for the raster is somewhat different: 0 to 1.24 million versus 1 to 1.17 million.

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