Atlas 2020 tetrad coverage in a vc

[AndyAmphlett]

Hi,

after reading Kevin Walker and and Paul Smith’s document on recording for Atlas 2020, I set about creating an Excel file that I would find useful for my vc (vc94). I have added instructions how to adapt it to other vcs. It requires that you run two DDb queries, download a list of tetrads from BRC, and paste the data into the relevant worksheets, after deleting the vc94 data. Full instructions are included in the 'Read This' worksheet, with links to the DDb queries. A few folk have now tested this file and it works ok - using Excel 2007 or later anyway.

PLEASE NOTE: a revised version of this analysis spreadsheet is now available to download. See message dated 11th January 2015, below.

[AndyAmphlett]

Hi,

a revised version of the tetrad analysis spreadsheet (version 3) includes listing of hectads in a vc, number of tetrads per hectad, and number of tetrads that are 'well recorded' in each hectad. (Download link has been removed).

Andy.

PLEASE NOTE: a revised version of this analysis spreadsheet is now available to download. See message dated 11th January 2015, below.

[jimmcintosh]

This is really useful. Thank you Andy!!

If any recorders need help to use the spread sheet, let your Country Officer know and we can extract the data and run the analysis for you.

I hear Tom is working on an app which will list all tetrads/monads in Irish Vice-counties and tell you what percentage is land and sea - just like the BRC Resources app does for GB.

Best
Jim

[AndyAmphlett]

Hi,

A revised version of the Atlas 2020 tetrad coverage spreadsheet has been created, with input from Jim McIntosh. This supercedes previous versions. The web address for downloading a list of tetrads in a vc from BRC had changed, and the format of the download had also changed. This revised spreadsheet incorporates these changes. The Analysis worksheet now allows the user (typically a VCR) to vary three input parameters. The minimum number of species per tetrad (default 100); the proportion of species recorded since 2000 (default 0.75, ie 75%); and the target number of tetrads to record per full hectad (default 5). Please do not uncritically accept these defaults, other values might well be more appropriate in your vc.

The link to the revised spreadsheet (version 4) is:

Download link has been removed.

PLEASE NOTE: a revised version of this analysis spreadsheet is now available to download. See message dated 11th January 2015, below.

Andy.

[AndyAmphlett]

Hi,

the method used in the most recent version of the Excel file (December 2014), for the pro-rata calculation of number of tetrads to record in part hectads, somewhat inflated the number of tetrads to be recorded. I have therefore changed the calculation method. A graphic showing how numbers of tetrads per part hectad will be calculated for different targets is shown in the Analysis worksheet.

Previous versions of the Excel file, included all tetrads, no matter how small the area in a vice-county, when carrying out calculations of numbers of tetrads to record. Especially where a vc has a long and complex boundary, this also tended to inflate the calculated number of tetrads to record. I have therefore modified the Analysis worksheet to give two sets of results. One, that meets a 'Low threshold' and the other that meets a 'High threshold'.

The Low threshold is: Target number of tetrads to survey for 'well recorded hectad' is based on number of tetrads in hectad with at least 1km2 of land & fresh water in the vice-county.
The High threshold is: Target number of tetrads to survey for 'well recorded hectad' is based on number of tetrads in hectad, irrespective of area of land & fresh water in the vice-county.

The hectad summary table on the Analysis sheet now has two colours of conditional formatting, distinguishing hectads that meet the Low cf High thresholds.

I have updated the 'Read this' worksheet to reflect these changes.

The link to download the latest version of the Excel file is:

https://dl.dropboxusercontent.com/u/404 ... le%29.xlsx

Please download the file, and experiment with varying the three input parameters (cells R3, R4 and R6 on the Analysis worksheet), to see what effect changes have. Then substitute the current vc94 data with that for your vc, or a vc of interest. The file is a tool to assist with planning field work and assessing progress towards Atlas 2020, so please vary the input parameters and interpret outputs to best meet your requirements.

Andy.

[jimmcintosh]

Excellent thank you Andy! Thanks very much for investigating and fixing this issue. I’ve rerun the Analysis for Shetland and it makes a huge difference there – due to its very complicated coastline, and loads of small bits of land at the edges of squares.

With the high threshold, there are 82 tetrads to survey - but with the low threshold just(!) 55. Still very worrying but slightly less worrying!

Jim

[VCR111]

Following analysis of well-recorded tetrads/hectads pre- and post 2000, the next obvious thing is to look more closely at ones of particular interest (e.g. I have one hectad that I thought was particularly well recorded but is not showing as such on the colour-coded map) and see which species have been missed. Can we have a query that shows pre- and post-2000 species lists per tetrad and hectad?

[welshofficer]

I think the following query should do what you want, if I've understood you right. I've put it from 1987 but you can change that to an earlier date if you wish. It has species before and after 2000 and if you click on pre-2000 and 2000- it should sort them. Probably best downloaded and sorted in Excel.

http://bsbidb.org.uk/search.php#retriev ... 5ec7e3a7a0

[admin]

Hi John,

I've updated the on-line version of the reports (which is functionally similar to Andy's spreadsheet) to link directly to search results for the various subdivided tetrad taxon lists. The summary page is accessible from your 'My County' report (link at top right of DDb webpage).

On the third tab of the county summary report ('Atlas 2020 survey coverage)', scroll down to the second data table (headed 'tetrad-level coverage'). The table provides similar information to the spreadsheet version, but the species totals for each tetrads are links to search results listing the corresponding taxa.

Further improvements to the 'My County' report pages are planned soon.

regards,

Tom

[VCR111]

Thank you Paul and Tom for replies. Impressive!