[NatureNS] Estimating (guessing) numbers of birds

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From: Graham Williams <grahamevanwilliams@gmail.com>
Date: Wed, 10 Jul 2013 07:42:53 -0400
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I used to use a lot of x's in my ebird submissions until someone told me tha=
t scientists behind ebird actually preferred estimates since count data can a=
lways be converted to presence/absence but the opposite is not true.=20

Ebird has some good reference material under the help section that provides t=
he logic behind preferring estimates over x's. Here is a link:=20

http://help.ebird.org/customer/portal/articles/1006732-the-trouble-with-x---=
why-you-should-always-estimate-numbers-

Ebird also has a two part tutorial on how to count and/or estimate numbers o=
f birds in large flocks. I found these articles to be very helpful.=20

http://ebird.org/plone/ebird/news/bird-counting-101

http://ebird.org/plone/ebird/news/bird-counting-201

Cheers,
Graham Williams
Longwood, Fl


Sent from my iPhone

On Jul 9, 2013, at 9:32 AM, Nancy P Dowd <nancypdowd@gmail.com> wrote:

> You have convinced me to submit my sightings as numbers on eBird. Now I wi=
ll have to persuade my brother (a statistics prof himself) of this.=20
>=20
> He still feels that presence/absence (x or blank) is the only reliable rep=
ort for these bird surveys. Despite the limited statistical analysis that ca=
n be done on such data.=20
>=20
> Nancy
>=20
> Sent from my iPhone
>=20
> On 2013-07-08, at 12:12 PM, iamclar@dal.ca wrote:
>=20
>> All:
>>=20
>> Nancy's dilemma and suggestions on estimating numbers for eBird are impor=
tant. I have been a frequent user of eBird, atlas, CBC, BBS, etc., over the y=
ears in estimating trends and patterns,. I believe the dictum of a statistic=
ian colleague that "a large number of bad numbers (as long as not biassed) a=
re as good as a small number of good numbers" (a recasting of the "law of la=
rge numbers"). Even the casual reporting of numbers like "lots" or "common" o=
n naturens are less useful for section editors of "NS Birds" than are estima=
tes.
>>=20
>> Nancy suggests that a range of categories could be available on eBird 2-1=
0, 11-50, etc., but the "users" of these numbers would still have to turn th=
ese into a single number for trend analyses, etc. I believe that an educated=
 guess is better; Why not just take the rough number between 11 and 50, e,g.=
, that you think might be better - 20 or 40?
>>=20
>> Another possible guide might be that used during the first (1980s) NS Atl=
assers of entering log categories 1-10, 10-100, etc. (natural logs even bett=
er). Then (as was done) the user (or indeed the observer) can use the geomet=
ric mean (about 3, about 30, etc.).
>>=20
>> Cheers, Ian
>>=20
>> Ian McLaren
>>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div style=3D"-webkit-text-size-adjust: aut=
o; ">I used to use a lot of x's in my ebird submissions until someone told m=
e that scientists behind ebird actually preferred estimates since count data=
 can always be converted to presence/absence but the opposite is not true.&n=
bsp;</div><div style=3D"-webkit-text-size-adjust: auto; "><br></div><div sty=
le=3D"-webkit-text-size-adjust: auto; ">Ebird has some good reference materi=
al under the help section that provides the logic behind preferring estimate=
s over x's. Here is a link:&nbsp;</div><div style=3D"-webkit-text-size-adjus=
t: auto; "><br></div><div><a href=3D"http://help.ebird.org/customer/portal/a=
rticles/1006732-the-trouble-with-x---why-you-should-always-estimate-numbers-=
">http://help.ebird.org/customer/portal/articles/1006732-the-trouble-with-x-=
--why-you-should-always-estimate-numbers-</a><font face=3D".HelveticaNeueUI"=
><span style=3D"font-size: 15px; line-height: 19px; white-space: nowrap; -we=
bkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fi=
ll-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rg=
ba(77, 128, 180, 0.230469);"><br></span></font><br>Ebird also has a two part=
 tutorial on how to count and/or estimate numbers of birds in large flocks. I=
 found these articles to be very helpful.&nbsp;</div><div><br></div><div><a h=
ref=3D"http://ebird.org/plone/ebird/news/bird-counting-101">http://ebird.org=
/plone/ebird/news/bird-counting-101</a></div><div><br></div><div><a href=3D"=
http://ebird.org/plone/ebird/news/bird-counting-201">http://ebird.org/plone/=
ebird/news/bird-counting-201</a></div><div><br></div><div>Cheers,</div><div>=
Graham Williams</div><div>Longwood, Fl</div><div><br><br><span style=3D"-web=
kit-text-size-adjust: auto;">Sent from my iPhone</span></div><div style=3D"-=
webkit-text-size-adjust: auto; "><br>On Jul 9, 2013, at 9:32 AM, Nancy P Dow=
d &lt;nancypdowd@gmail.com&gt; w=
rote:<br><br></div><blockquote type=3D"cite" style=3D"-webkit-text-size-adju=
st: auto; "><div><span>You have convinced me to submit my sightings as numbe=
rs on eBird. Now I will have to persuade my brother (a statistics prof himse=
lf) of this. </span><br><span></span><br><span>He still feels that presence/=
absence (x or blank) is the only reliable report for these bird surveys. Des=
pite the limited statistical analysis that can be done on such data. </span>=
<br><span></span><br><span>Nancy</span><br><span></span><br><span>Sent from m=
y iPhone</span><br><span></span><br><span>On 2013-07-08, at 12:12 PM, <a hre=
f=3D"mailto:iamclar@dal.ca">iamclar@dal.ca</a> wrote:</span><br><span></span=
><br><blockquote type=3D"cite"><span>All:</span><br></blockquote><blockquote=
 type=3D"cite"><span></span><br></blockquote><blockquote type=3D"cite"><span=
>Nancy's dilemma and suggestions on estimating numbers for eBird are importa=
nt. I have been a frequent user of eBird, atlas, CBC, BBS, etc., over the ye=
ars in estimating trends and patterns,. I believe the dictum of a statistici=
an colleague that "a large number of bad numbers (as long as not biassed) ar=
e as good as a small number of good numbers" (a recasting of the "law of lar=
ge numbers"). Even the casual reporting of numbers like "lots" or "common" o=
n naturens are less useful for section editors of "NS Birds" than are estima=
tes.</span><br></blockquote><blockquote type=3D"cite"><span></span><br></blo=
ckquote><blockquote type=3D"cite"><span>Nancy suggests that a range of categ=
ories could be available on eBird 2-10, 11-50, etc., but the "users" of thes=
e numbers would still have to turn these into a single number for trend anal=
yses, etc. I believe that an educated guess is better; Why not just take the=
 rough number between 11 and 50, e,g., that you think might be better - 20 o=
r 40?</span><br></blockquote><blockquote type=3D"cite"><span></span><br></bl=
ockquote><blockquote type=3D"cite"><span>Another possible guide might be tha=
t used during the first (1980s) NS Atlassers of entering log categories 1-10=
, 10-100, etc. (natural logs even better). Then (as was done) the user (or i=
ndeed the observer) can use the geometric mean (about 3, about 30, etc.).</s=
pan><br></blockquote><blockquote type=3D"cite"><span></span><br></blockquote=
><blockquote type=3D"cite"><span>Cheers, Ian</span><br></blockquote><blockqu=
ote type=3D"cite"><span></span><br></blockquote><blockquote type=3D"cite"><s=
pan>Ian McLaren</span><br></blockquote><blockquote type=3D"cite"><span></spa=
n><br></blockquote></div></blockquote></body></html>=

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