User:Roboduckie01/sandbox

Summary
This activity will recreate part of the design of a classification method for the the Cocholotoma septemspirale snail. By observing multiple traits of the shells, the original researchers were able to decide on a series of dimorphisms (difference in forms) between male and female snails.

This data set is a reduced version of the Sexual Dimorphism in Snails dataset, found here: [insert link to that set]

Goals
This activity will guide students through the use of a 2 x 3 Two-way ANOVA and post-hoc t-tests.

Data Summary

 * Number of cases: 112
 * Variables Names:
 * Sex: Sex of the snail; 1 = female, 2 = male
 * Location: Where the snail was found in Switzerland; 1 = Chasseral, 2 = Orvine, 3 = Combes de Nods
 * shell.h Height of the shell, in micrometers
 * shell.w Width of the shell, in micrometers
 * aperture.h Height of the shell aperture (where the snail comes out of), in micrometers
 * aperture.w Height of the shell aperture, in micrometers
 * whorl.w Width of the last whorl (spiral section) on the shell, in micrometers.
 * rib.n Number of ribs on the last whorl on the shell, in micrometers.

Data Analysis
Begin by selecting "sex" and "locality" as the independent variables. Next, select one of the four shell five shell measures as your dependent variable. We will use "ribs" in the following example, but it is recommended that you use another in its place to explore these measures.

Begin by using the Two-Way Anova. Copy and paste data from this page into the cells provided by the applet. Use the ctrl + c command and the "paste" button in the applet to paste the sex, locality, and ribs. [Insert SnailPagePic1]

Click on the mapping tab and select the independent and dependent variables. Turn interaction on, and press the calculate button. This should bring up the results page. [Image of the results].

Note that because this is a 2 x 3 ANOVA, the significance of the main effect for sex is the significance value for the difference between ale and female.

However, for the main effect of locality, you will need to conduct a t-test for each of the three pairs. You can do this in a similar manner to the two-way ANOVA.

Reference
Reichenbach F, Baur H, Neubert E (2012) Sexual dimorphism in shells of Cochlostoma septemspirale (Caenogastropoda, Cyclophoroidea, Diplommatinidae, Cochlostomatinae). ZooKeys 208: 1-16. doi:10.3897/zookeys.208.2869

Baur H, Reichenbach F, Neubert E (2012) Data from: Sexual dimorphism in shells of Cochlostoma septemspirale (Caenogastropoda, Cyclophoroidea, Diplommatinidae, Cochlostomatinae). Dryad Digital Repository. doi:10.5061/dryad.ns7v7


 * SOCR Home page: http://www.socr.ucla.edu