If I read your problem correctly, an experiment is not really being conducted. Rather, it is a static group comparison which is essentially a pre-experimental design. The pollutants, fish, and rivers are not "manipulated" by the researcher. The manipulation of independent variables is the sine qua non of an experiment. Regardless, it would be feasible to determine the relationships among fish diversity, pollution levels, pH levels, etc. comparing randomly selected rivers.
On 20 Feb 2002 11:30:00 -0800, [EMAIL PROTECTED] (Voltolini) wrote: >Hi, > >I was reading a definition of "experiment" in science to be used in a >lecture and the use of treatments and controls are an important feature of >an experiment but.... my doubt is... is it possible to plan an experiment >without a control and call this as an "experiment" ? > >For example, in a polluted river basin there is a gradient of contamination >and someone are interested in to compare the fish diversity in ten rivers of >this basin. Then, the "pollution level" are the treatment (with ten levels) >but if there is not a clean river in the basin, I cannot use a control ! > >Is this an experiment anyway ? > > > Thanks for any comments..... > Voltolini > >_____________________________________________ > >Prof. J. C. VOLTOLINI >Grupo de Estudos em Ecologia de Mamiferos - ECOMAM >Universidade de Taubate (UNITAU) >Departamento de Biologia >Taubate, SP, Brasil. CEP 12030-010 >Tel: 0XX12-2254165 (lab.), 2254277 (secret. depto.) >FAX: 12 - 2322947 >E-Mail: [EMAIL PROTECTED] >_____________________________________________ > > > >================================================================= >Instructions for joining and leaving this list, remarks about the >problem of INAPPROPRIATE MESSAGES, and archives are available at > http://jse.stat.ncsu.edu/ >================================================================= ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at http://jse.stat.ncsu.edu/ =================================================================
