1 Topic by charliebarnes

  • charliebarnes
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Topic: Accuracy of inferred vice-county

Following on from:

sratcliffe wrote:

the Atlas will still infer the vice county from the grid reference and use that inferred value in the searches.

How accurate is this? I.e. Does the Atlas do a proper polygon within polygon search for each grid ref associated with the record?

Charlie Barnes
Information Officer
Greater Lincolnshire Nature Partnership

charliebarnes's Website

2 Reply by Tom Humphrey

  • Tom Humphrey
  • Tom Humphrey
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Re: Accuracy of inferred vice-county

It might also be interesting to know how ambiguous (boundary spanning) grid-squares are handled.

Would the record be reported as present in multiple counties; only in the county that has the greater part of the square; or arbitrarily assigned to one of the intersected counties?

Tom Humphrey
Database Officer,
Botanical Society of Britain and Ireland (BSBI)

Tom Humphrey's Website

3 Reply by sratcliffe

  • sratcliffe
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Re: Accuracy of inferred vice-county

I have asked the ALA developer about this and I will let you know his reply as soon as I have it.

Thanks, Sophie

4 Reply by sratcliffe (edited by sratcliffe 06-03-2018 13:05:51)

  • sratcliffe
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Re: Accuracy of inferred vice-county

I made a mistake: the Atlas doesn't do polygon within polygon search using the grid reference.

GRs are converted into latitude and longitude points, and those points are then used for the sampling. There maybe inconsistencies with grid cells near boundaries and the uncertainty or resolution of the record isn't taken into account.