You analyze the data including all data points. Then, you examine the influential outliers. If the influential outliers are influential due to a known bias that was external to the conditions in the experiment, you can remove them. You may need to change your statistical test due to changes in your dataset after their removal. Report EVERYTHING you did in your paper. Malcolm
On Tue, Jun 5, 2012 at 5:54 PM, Timothy Wertin <[email protected]> wrote: > We are trying to calculate relative growth rate of perennial grass > species. We have a large number of tagged individuals with which we > estimate biomass each year. Naturally, every year we experience at least > a few mortality events, which are evenly distributed across our treatments > (warming, watering and warming x watering). > > Could someone(s) please advise on how you would calculate RGR when you > have a mortality that does not appear driven by treatment? Do you remove > the sample from the population the year it dies? Do you remove completely > from the analysis? > > A hypothetical example: Population RGR from 2009 - 2010 was -0.12. In > 2011 an individual died resulting in that individual's RGR from 2010 to > 2011 of -20, and a population RGR from 2010 to 2011 of -3. The individual > is removed from the population 2010 - 2011 RGR calcuation and now the > population RGR goes to 0.1. It is likely that the population RGR from > 2009-2010 was negative because the plant was dying. Note: the plant was > not damaged, subjected to an insect event and in general appeared the same > as other plants in the experiment. > > Thanks! > Tim Wertin > USGS - Canyonlands Research Station -- Malcolm L. McCallum Department of Molecular Biology and Biochemistry School of Biological Sciences University of Missouri at Kansas City Managing Editor, Herpetological Conservation and Biology "Peer pressure is designed to contain anyone with a sense of drive" - Allan Nation 1880's: "There's lots of good fish in the sea" W.S. Gilbert 1990's: Many fish stocks depleted due to overfishing, habitat loss, and pollution. 2000: Marine reserves, ecosystem restoration, and pollution reduction MAY help restore populations. 2022: Soylent Green is People! The Seven Blunders of the World (Mohandas Gandhi) Wealth w/o work Pleasure w/o conscience Knowledge w/o character Commerce w/o morality Science w/o humanity Worship w/o sacrifice Politics w/o principle Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.
