Re: [MORPHMET] question Elliptic Fourier Descriptors
Dear Carmelo, Thanks for the help. We already performed multivariate analyses, but decided to highlight the most important PCs separately as well. I now also performed the residual analysis, suggested by Marcello. Kind regards, Jens On Tuesday, October 27, 2015 at 12:15:27 AM UTC+1, Carmelo Fruciano wrote: > > Dear Jens, > you might want to consider working with multivariate analyses (i.e. > using all PCs and not a single one) and, as it has been suggested, > using (multivariate) linear models rather than dividing scores by your > size measure. > Best, > Carmelo > > > -- > Carmelo Fruciano > Honorary Fellow - University of Catania - Catania, Italy > e-mail c.fru...@unict.it > http://www.fruciano.it/research/ > > > > Jens De meyer > ha scritto: > > > Dear, > > > > I have a question about EFDs, and was wondering if you could help > > me? I have performed a PCA on standardized EFDs (standardized for > > first harmonic, using SHAPE-software). The EFDs represented head > > shapes of eels which were given different diets (we compared three > > different diets). The results of the PCA indicated that PC1 was > > related to variation in head width, with high PC-scores being > > related to broader heads and vice versa. Next, we performed a linear > > regression on these PC-scores and log(length) of the three different > > diets and observed a size-effect in all three diets. > > Because of this, I wanted to divide the PC-scores by the total > > length of the studied eels. Then, we would perform an ANOVA on these > > length-corrected PC-scores between the different diets, as this > > would allow us to find out whether the mean head width of a certain > > diet is significantly broader than another diet. > > Therefore, my question to you is: Am I acutally allowed to divide > > these PC-scores by total length? > > Many thanks in advance! > > Kind regards, > > Jens De Meyer > > > > -- > > MORPHMET may be accessed via its webpage at http://www.morphometrics.org > > > > To unsubscribe from this group and stop receiving emails from it, > > send an email to morphmet+u...@morphometrics.org . > > > > > > -- > Carmelo Fruciano > Honorary Fellow - University of Catania - Catania, Italy > e-mail c.fru...@unict.it > http://www.fruciano.it/research/ > > -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
Re: [MORPHMET] question Elliptic Fourier Descriptors
Dear Marcello, Thank you for your response. I now performed the analysis suggested by you. Kind regards, Jens On Monday, October 26, 2015 at 2:38:52 PM UTC+1, marcelo.cardillo wrote: > > If you want to use "free size effect data" I think it can be good idea > use the residuals of the regression between the PC and log(lengh), because > this residuals are new variables not explained by size. > > best > M > > 2015-10-26 9:42 GMT-03:00 Jens De meyer > >: > >> Dear, >> >> I have a question about EFDs, and was wondering if you could help me? I >> have performed a PCA on standardized EFDs (standardized for first harmonic, >> using SHAPE-software). The EFDs represented head shapes of eels which were >> given different diets (we compared three different diets). The results of >> the PCA indicated that PC1 was related to variation in head width, with >> high PC-scores being related to broader heads and vice versa. Next, we >> performed a linear regression on these PC-scores and log(length) of the >> three different diets and observed a size-effect in all three diets. >> Because of this, I wanted to divide the PC-scores by the total length of >> the studied eels. Then, we would perform an ANOVA on these length-corrected >> PC-scores between the different diets, as this would allow us to find out >> whether the mean head width of a certain diet is significantly broader than >> another diet. >> Therefore, my question to you is: Am I acutally allowed to divide these >> PC-scores by total length? >> Many thanks in advance! >> Kind regards, >> Jens De Meyer >> >> -- >> MORPHMET may be accessed via its webpage at http://www.morphometrics.org >> >> To unsubscribe from this group and stop receiving emails from it, send an >> email to morphmet+u...@morphometrics.org . >> > > > > -- > Dr.Marcelo Cardillo > IMHICIHU-CONICET-UBA > Saavedra 15, 5to piso cp (1083) > Teléfono: (011) 4953-8548 - Interno 212 > Buenos Aires. Capital Federal. Argentina > http://conicet.academia.edu/MarceloCardillo > -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
Re: [MORPHMET] question Elliptic Fourier Descriptors
Dear Jens, you might want to consider working with multivariate analyses (i.e. using all PCs and not a single one) and, as it has been suggested, using (multivariate) linear models rather than dividing scores by your size measure. Best, Carmelo -- Carmelo Fruciano Honorary Fellow - University of Catania - Catania, Italy e-mail c.fruci...@unict.it http://www.fruciano.it/research/ Jens De meyer ha scritto: Dear, I have a question about EFDs, and was wondering if you could help me? I have performed a PCA on standardized EFDs (standardized for first harmonic, using SHAPE-software). The EFDs represented head shapes of eels which were given different diets (we compared three different diets). The results of the PCA indicated that PC1 was related to variation in head width, with high PC-scores being related to broader heads and vice versa. Next, we performed a linear regression on these PC-scores and log(length) of the three different diets and observed a size-effect in all three diets. Because of this, I wanted to divide the PC-scores by the total length of the studied eels. Then, we would perform an ANOVA on these length-corrected PC-scores between the different diets, as this would allow us to find out whether the mean head width of a certain diet is significantly broader than another diet. Therefore, my question to you is: Am I acutally allowed to divide these PC-scores by total length? Many thanks in advance! Kind regards, Jens De Meyer -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org. -- Carmelo Fruciano Honorary Fellow - University of Catania - Catania, Italy e-mail c.fruci...@unict.it http://www.fruciano.it/research/ -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
Re: [MORPHMET] question Elliptic Fourier Descriptors
If you want to use "free size effect data" I think it can be good idea use the residuals of the regression between the PC and log(lengh), because this residuals are new variables not explained by size. best M 2015-10-26 9:42 GMT-03:00 Jens De meyer : > Dear, > > I have a question about EFDs, and was wondering if you could help me? I > have performed a PCA on standardized EFDs (standardized for first harmonic, > using SHAPE-software). The EFDs represented head shapes of eels which were > given different diets (we compared three different diets). The results of > the PCA indicated that PC1 was related to variation in head width, with > high PC-scores being related to broader heads and vice versa. Next, we > performed a linear regression on these PC-scores and log(length) of the > three different diets and observed a size-effect in all three diets. > Because of this, I wanted to divide the PC-scores by the total length of > the studied eels. Then, we would perform an ANOVA on these length-corrected > PC-scores between the different diets, as this would allow us to find out > whether the mean head width of a certain diet is significantly broader than > another diet. > Therefore, my question to you is: Am I acutally allowed to divide these > PC-scores by total length? > Many thanks in advance! > Kind regards, > Jens De Meyer > > -- > MORPHMET may be accessed via its webpage at http://www.morphometrics.org > > To unsubscribe from this group and stop receiving emails from it, send an > email to morphmet+unsubscr...@morphometrics.org. > -- Dr.Marcelo Cardillo IMHICIHU-CONICET-UBA Saavedra 15, 5to piso cp (1083) Teléfono: (011) 4953-8548 - Interno 212 Buenos Aires. Capital Federal. Argentina http://conicet.academia.edu/MarceloCardillo -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
[MORPHMET] question Elliptic Fourier Descriptors
Dear, I have a question about EFDs, and was wondering if you could help me? I have performed a PCA on standardized EFDs (standardized for first harmonic, using SHAPE-software). The EFDs represented head shapes of eels which were given different diets (we compared three different diets). The results of the PCA indicated that PC1 was related to variation in head width, with high PC-scores being related to broader heads and vice versa. Next, we performed a linear regression on these PC-scores and log(length) of the three different diets and observed a size-effect in all three diets. Because of this, I wanted to divide the PC-scores by the total length of the studied eels. Then, we would perform an ANOVA on these length-corrected PC-scores between the different diets, as this would allow us to find out whether the mean head width of a certain diet is significantly broader than another diet. Therefore, my question to you is: Am I acutally allowed to divide these PC-scores by total length? Many thanks in advance! Kind regards, Jens De Meyer -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
