Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

From |
Jacob Felson <felsonj@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Re: choice of ANOVA for an ecological experiment |

Date |
Mon, 31 Jan 2011 12:27:44 -0500 |

Carlo, Good question. I've also done a MANOVA, yes. For the MANOVA as well, I'm wondering about the appropriate way to analyze the data -- split plot or something else. Jacob Felson On Sun, Jan 30, 2011 at 3:00 PM, Jacob Felson <felsonj@gmail.com> wrote: > Hello, > > I am wondering whether anyone might be able to advise me about the > best choice of ANOVA to analyze the results of an ecological > experiment. In each of eight ponds, a certain number of various > species were put into enclosures that were randomly assigned to a set > of four predator conditions. The four randomly assigned predator > conditions were: no predators, 8 predators, 16 predators, and 24 > predators. Each predator condition was assigned to 3 replicates. So > the total number of enclosures was: 8 ponds x 4 predator conditions x > 3 replicates = 96. The outcome variables include the number of > individuals remaining, the weight of the individuals remaining, and > the size of the individuals remaining. > > This experiment appears to follow a split-plot design. Is this > correct? That is, the error of the pond effect is distinct from the > error of the predator condition effect. The sum of squared error for > the pond would be equal to the sum of squares for the predator > condition. The sum of squared error for the predator condition would > be equal to the residual sum of squares. > > The predator condition variable is called density, and the outcome > variable is number of survivors. If all of this is accurate, then I'm > guessing that a simple model might be: > > anova survivors pond / density | pond / > > > Is this correct? One further issue is that the ponds are fixed, not > random. Unlike the textbook split-plot design, a whole-plot has not > been randomly assigned to ponds. Instead, there are simply 8 ponds, > within each of which individuals were collected and placed in > enclosures with varying predator conditions. > > > I would very much appreciate help on this issue! > > > Sincerely, > Jacob Felson > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: R: Re: choice of ANOVA for an ecological experiment***From:*"Carlo Lazzaro" <carlo.lazzaro@tin.it>

**References**:**st: choice of ANOVA for an ecological experiment***From:*Jacob Felson <felsonj@gmail.com>

- Prev by Date:
**Re: st: Sample selection correction models with fixed-effects** - Next by Date:
**re: st: choice of ANOVA for an ecological experiment** - Previous by thread:
**st: R: choice of ANOVA for an ecological experiment** - Next by thread:
**st: R: Re: choice of ANOVA for an ecological experiment** - Index(es):