Date: Tue, 16 Mar 2004 18:35:58 -0500 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: "Frederick W. Fallon" Subject: Re: Scoter numbers MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Yes, actually you can. This situation often arises in sums of estimates. The errors add "vectorally", so the larger error dominates the error of the result. In this case, e.g. 114,400 "+/-" 1,000 + 41,000 +/- 400 + 22 +/- 0 = 155,422 +/- sqrt[(1,000)^2 +(400)^2 +(0)^2]= 155,422 +/- 1,070. Since the error is so large, one could reasonably round to "155,000 +/- 1,000" as a final result; but if the sum were to be used and combined with other numbers for some purpose, the precise sum should be used and then the "final" final result (whatever that was) would have its error separately calculated according to what function was used to get it. I hope this helps. Fred Fallon Bowie fwfallon@earthlink.net "George M. Jett" wrote: > > Jim > > I will ask a PhD statistician friend of mine if you can have an exact > number which is composed of estimates and actual numbers. Looks goofy > to me. There was no mention of the +/- 10 percent provided in the > original message. I also would not want to count 155,422 separate > scoters. Including the estimates seems to dilute the exactness of the > count. > > George > > Henry > > You have been to college for this subject. What do you say. > > I am well, hope you are the same. > > Thanks. > > George > > ----- Original Message ----- > From: "JAMES FELLEY" > To: > Sent: Tuesday, March 16, 2004 9:11 AM > Subject: [MDOSPREY] Scoter numbers > > > George Jett wondered: > > > > >How can you have an exact number of "155,422 scoters" if you have > > >estimated the number of Black Scoters as "About 41,000"? > > > > Simple! Try these numbers as an example: > > Black Scoters - about 41,000 > > Surf Scoters - about 114,400 > > White-winged scoters - exactly 22 > > > > Sum = 155,422 scoters, (plus or minus 10%, which would be > > "about 15,000") > > > > Why disrespect the White-winged Scoters by ignoring > > them in the total count? > > > > (semi-seriously) Jim > > > > Jim Felley > > Smithsonian Institution > > felleyj@si.edu > > > > ==================================================================== > > === > > To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com > > with the following message in line 1: signoff mdosprey > > ======================================================================= > > > > ====================================================================== > = > To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com > with the following message in line 1: signoff mdosprey > ======================================================================= ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================