show content availability for current choices

[graybeal]

Is your feature request related to a problem? If so please describe.
Can't tell whether any content is available for chosen variable-location type-location items.

Describe the solution you'd like

• Any time user updates the location type, location list items, or selected variables, an indication of data availability should be present for all the statistical variables.
  • Minimum is that each statistical variable show whether data are available for that variable given current settings; better is to show percentage of the specific location items which have that variable.
  • In any case, answer must be available by location type, and could also be shown by location items (e.g, each zip code).
• If variable(s) are entered before location type, show the availability (percentage) across all the location types.
  • This lets user choose the best location types for their variables
  • Also as secondary priority if location type has been specified.

Describe alternatives you've considered

• Best way to present multivariate availability (in variable x location types and variable x location items cases) is unclear.
  • There are fewer location types so showing those horizontally for each variable could work
  • If the entry interface were a blank spreadsheet with locations entered in column 1 and variables in row 1, availability could be displayed on the fly. Ditto if location types were the top few items in column 1 of the blank spreadsheet.
• Not displaying or graying out the variables that do not have data available for the location type. (This could be a configuration.)
• How many rows of data are available for a given location type is a poor proxy for the percentage, but much better than just a check mark
• Not updating the availability whenever location information changes (because that could be expensive).

Additional context

• When time ranges are introduced, availability should reflect the given time range as well.
• More complex/subtle availability controls will be needed eventually (e.g. so I can see if more data is available in another location type).