Document codes and data structures associated with the EIA 176

[zaneselvans]

The full dataset can be downloaded from here, and consists of about 60MB worth of CSVs (uncompressed). Lots of data about natural gas production and consumption.

[karldw]

Things I've learned this morning:

• The LINE variable is the form line number multiplied by 100
  • For a couple of fields, the question associated with the line number has changed over time (see https://www.eia.gov/naturalgas/ngqs/ngqs_user_guide.pdf#page=21)
• The ATYPE variable refers to the column of the answer. For the questions I'm interested in, VL is gas volume in 1000s of cubic feet, CS is revenue in dollars, and CT is customer count. I figured these out by comparing the numbers in the bulk download with the data browser. I'm not sure if they're documented somewhere.
• There are duplicates for name-state-year, even when ID-state-year is unique.

[zaneselvans]

Reopening with a more prescribed scope since we are going to integrate this data, and Karl has done some data sleuthing already.

[MichaelTiemannOSC]

Noting that 176 can and should be cross-checked against 857

https://www.eia.gov/dnav/ng/TblDefs/NG_DataSources.html#s176
https://www.eia.gov/dnav/ng/TblDefs/NG_DataSources.html#s857

[zaneselvans]

I think this is superceded by the subtasks within #2603 now.