Before and after are repeated measures issues if using an ANOVA or T-test. Are the data continuous or categories?
If continuous you can use a regression. If categories then use ANOVA/T-Test. The bottom line is that we do not know enough about the nature of the data and the area to advise you in any more in-depth capacity. There are a variety of assumptions for each kind of test, and none of these are really addressed in your email. Try this website for advice: http://www.statsoft.com/textbook/ On Wed, Nov 14, 2012 at 3:03 AM, Gurmeet Singh <gurmee...@gmail.com> wrote: > Dear ECOLOG member > > > > *I urgently require your suggestions related to statistical approaches to > the following problem* > > > > *The Problem* > > I have been working on a coastal forest ecosystem and its sedimentary > biogeochemical processes. Recently due to cyclonic event, the area was > suddenly flash-flooded. The flood supposedly disturbed the sediment column > as well as retreating water deposited waste load . > > > > *Approach* > > Sediment cores (n=10) , collected from the area immediately after the > flood and sectioned at 5 cm interval for the geochemical analysis. > > > > *Hypothesis* > > *The flood has resulted in significant changes in the sediment column > biogeochemistry .* > > > The hypothesis is well supported by the experimental results . Geochemical > analysis of the cores at 5 cm interval indicates trends of deposition of > fresh sediments/disturbance/waste deposition > > > > > > *Statistical approaches* > > > > > 1. .Entire forest area cover is disturbed due to cyclonic flood i.e. the > spatial variation in the geochemical characteristics are not significant > > 2. The sediment columns has been disturb due to deposition I.e > variation in the geochemical characteristics along with depth are > significant . > > > > > *Help Needed* > > * * > > *Which test of significance will be more suitable. * > > *I have applied ANOVA but have been getting conflicting response that * > > * * > > *" This is not totally appropriate for the samples collected especially in > sediment cores. Certain geochemical processes occur **down a sediment > column and there could be relations between samples. Therefore, the samples > (from different depth of a core) should not be treated as independent > samples and should not analyzed by using ANOVA ."* > > > > > Indeed, I have treated the different sections of a core along with depth as > individual independent samples and have compared with the correspond values > of other cores at any given depth. > > > > *Now I am confused whether my approach is wrong or ANOVA can’t be applied > to the system ? What other statistical approached (apart from PCA) I can > do to check the significance of variation across depth* > > * * > > Any response in this regards will be highly appreciated . If you can > forward me the some of related research papers, I will be obliged . > Received response will be duely credited . > > > > Regards > > > > Dr. Gurmeet Singh > > Jawaharlal Nehru University > > New Delhi > > > > > ====================== -- 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.
