Hi, it is interesting that you get so different results between MANOVA and NPMANOVA. Would you mind sending me the data set as saved from PAST for me to look at? (I'm the author of PAST).
The standard 'Iris' test data set of Fisher gives quite similar results between MANOVA and NPMANOVA of PAST. In general, the NPMANOVA is expected to be less powerful (have higher p values) than MANOVA, I believe. Oyvind Hammer Natural History Museum University of Oslo On Fri, 9 Nov 2007, morphmet wrote: > Dear colleagues, > > We would like to take advantage of Dr. Slice's comments about MANOVA to > assess differences among species or biological groups. There are few > multivariate normality tests available, however it is often common that > Partial Warps (and therefore Relative Warps) from morphological > structures do not fit normality. Thus, we think this is the main reason > why Dr. Slice recommends the non-parametric alternatives for MANOVA. > More specifically our problem is that we obtain different results when > applying either of both parametric and non-parametric MANOVAS. > We are at the moment assessing the relationships between environmental > variables (remote sensing data) and morphological characters (geometric > morphometrics) in a group of Neotropical bats. Neither of both types of > variables fit normality very well. > However, what currently puzzle us is the fact that the MANOVA performed > in SPSS give us significant differences, while the np-MANOVA in PAST > gives us non significant differences. The contrast in magnitude > between both p-values is extreme. We havent yet looked at additional > indexes of overlap, confidence or robustness for p-values. > We will be grateful with any comments or suggestions. > Pablo Menendez > Pablo Jarrin > > > > -- > Replies will be sent to the list. > For more information visit http://www.morphometrics.org > > -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
