I'd say that an experiment is where the investigator can and does change at least one value of at least one explanatory variable.
[And is implicitly hoping to learn something about causation]. I'd welcome any correction to the above, which is improvised. I'd also strongly recommend saying "explanatory variables" rather than "independent variables"; saying "independent" causes all manner of confusion, but it may be different in Portuguese! -- J.E.H.Shaw [Ewart Shaw] [EMAIL PROTECTED] TEL: +44 2476 523069 Department of Statistics, University of Warwick, Coventry CV4 7AL, UK http://www.warwick.ac.uk/statsdept http://www.ewartshaw.co.uk 3 ((4&({*.(=+/))++/=3:)@([:,/0&,^:(i.3)@|:"2^:2))&.>@]^:([EMAIL PROTECTED]) <#:3 6 2 . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
