# Corey Sparks

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bio website utsa.academia.edu/CoreySparks location San Antonio, TX age member for 1 year, 10 months seen 2 days ago profile views 31

I am a biological anthropologist trained in demography and statistics. I'm currently doing work using a lot of spatial statistical methods (point pattern, spatial regression, and some spatial Bayesian methods) and applying them to lots of different problems in population science and public policy. I also maintain a strong interest in evolutionary theory as applied to human behavior. I teach graduate stats courses in linear models, hazard models and spatial statistics.

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 Sep14 comment Interpretation of spatial lag models the help file does: ?impacts will get you started, if you're looking for rules of thumb (i'm not a big fan), I doubt there are any. The best description i've seen is in the second edition of Applied Spatial Data analysis in R by Bivand et al, section 9.4, it goes through it pretty well Sep14 answered Interpretation of spatial lag models Apr28 comment Ripley's K Function and L Function for Point Patterns I would use the simulation (envelope()) function before I put any statements on that, you need to evaluate how many times you could observe similar values of L by chance Apr27 answered Ripley's K Function and L Function for Point Patterns Apr7 answered Looking for a test for shape comparison Mar25 comment What weights to use actually that's not so bad, sometimes weights are in the thousands, but those are typically population weights. Mar23 answered What weights to use Mar22 comment Test to show when diverging linear regression models are statistically different Isn't this just a parallel slopes question? do you want to know if the slope is the same in the two groups? Just put an interaction term in the model, and look at the parameter test for the interaction term Feb19 awarded Commentator Feb13 comment Cox proportional hazard model fit to complex survey data If you use a complex survey design, as the OP said, you must use the correct procedure for estimating the standard errors of the estimates, svycoxph does this, and extractAIC on a survey design object does not work Feb13 answered Cox proportional hazard model fit to complex survey data Feb5 comment Using Anselin Local Moran's I Values in Regression I agree with the OP, I don't know what it would mean in a model as an IV, I still stick with my statement that some sort of spatially structured model would be better suited for this kind of thing Feb5 answered Using Anselin Local Moran's I Values in Regression Jan26 awarded Yearling Jan17 comment Best analysis for count data as response variable But it is not strictly normal Jan17 awarded Editor Jan17 revised Best analysis for count data as response variable the family in the glm was wrong Jan17 answered Best analysis for count data as response variable Jan17 suggested suggested edit on Best analysis for count data as response variable Jan11 comment Does Mahalanobis distances have “significance” associated with them? oh, it's absolutely circular, but if you're wanting to see how well the clusters are distinguished from one another, then DFA or something like it is the way to go. The DFA typically will have a test statistics with it, like a Wilk's lambda or Pillai trace to test for differentiation between the groups, but if you have lots of observations, this can be a little conservative, I like the crossvalidation classification rate. This site may get you started: statmethods.net/advstats/discriminant.html But this is assuming you're using R, I know how to do it in sas too, using proc discrim