Assignment #12 - Structural Equation Modeling

For today's class you should have read Karels et al. 2008. In this paper, the authors built a structural equation model to describe factors 'causing' extinction in island birds. Your job is to create a DIFFERENT structural equation model from that described in Karels et al. 2008 and analyze the model using R. You will do this assignment with a partner. Provide me with a hand- or computer-drawn version of your path diagram. Note that the data set has a few variables that weren't included in Karels' model; feel free to use them. Also, as usual, send me a word document in which you answer the following questions:

1. How many 'parameters' and 'observations' are there in your system?

2. Provide me with the strength of all direct and indirect causes of extinctions (r values - don't give me r^2).

3. Provide me with the AIC, and goodness-of-fit of your model (in this case, the chi-square and p-value).

Data - As in Karels et al. 2008, be sure you log transform all variables used in your analysis. For all count variables, you will need to add "1" first, before log transforming, because log-transforming zero is not possible. Note that 'latitude' has negative values, so you should either take it out of the data, or, if you want to use that variable, you will have to first ensure that all the values are positive (absolute value or add a sufficient number to make all values > 0).