tbates

6 June 2014

1. OpenMx source tarballs are now up on our webserver (oops)
2. Nobody took the bait to build IFA models with OpenMx (as far as I know)
3. LISREL help

• Should we have type = “LISREL”?
• Implement plot() for lisrel
• Example in Rd using raw data and means matrices

tbates

library(pwr)
power.t.test(n = 300, delta = NULL, sd = 1, sig.level = 0.05, power = .8, type = "paired", alternative = "one.sided")
#      Paired t test power calculation 
# 
#               n = 300
#           delta = 0.1438957
#              sd = 1
#       sig.level = 0.05
#           power = 0.8
#     alternative = one.sided

tbates

library(OpenMx)
manifests = c("mpg", "disp", "gear")

# =============================
# = simple independence model =
# =============================
m1 <- mxModel("ind", type = "RAM",
	manifestVars = manifests,
	mxPath(from = manifests, arrows = 2),
	mxPath(from = "one", to = manifests),

tbates

# R version 3.0.3 (2014-03-06) -- "Warm Puppy"
source("http://openmx.psyc.virginia.edu/getOpenMxBeta.R")
library("OpenMx")
packageVersion("OpenMx") # [1] ‘999.0.0.3473’

data(demoOneFactor)  

manifests <- names(demoOneFactor) 
latents   <- c("G")  
model <- mxModel(model="One Factor", type="RAM",

tbates

message("load me with devtools::source_gist('11326436')")

tbates

# http://openmx.psyc.virginia.edu/getOpenMxBeta.R

if(version$major < 3) {
	stop("We don't have beta for R 2.15 or below. Consider upgrading to R 3.1?\n
	You can get this from http://cran.r-project.org/")
}
if (.Platform$OS.type == "windows") {
    if (!is.null(.Platform$r_arch) && .Platform$r_arch == "x64") {
        repos <- c('http://openmx.psyc.virginia.edu/testing/')
    } else {

tbates

# http://openmx.psyc.virginia.edu/getOpenMx.R
# run this as
# source_gist(11294078)
if (.Platform$OS.type == "windows") {
    if (!is.null(.Platform$r_arch) && .Platform$r_arch == "x64") {
        repos <- c('http://openmx.psyc.virginia.edu/packages/')
    } else {
        repos <- c('http://openmx.psyc.virginia.edu/32bit/')
    }
    install.packages(pkgs = c('OpenMx'), repos = repos)

tbates

# Generate a 25-item test
nItems = 25
nOptions = 4
passCriterion = 3 # or better

correct_answers = sample(c(1:nOptions), nItems, replace = TRUE)
 
# ===================================
# = Generate 10000 random responses =
# ===================================

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# mixture distribution..
n = 100000;
distOne = rnorm(n,  50, 10)
distTwo = rnorm(n, 120, 15)
x = c(distOne,distTwo)
hist(x)
psych::kurtosi(x);psych::skew(x);

# DV <- sum of unobserved IVs
x = distOne + distTwo

tbates

# Things you should learn in school: Be able to answer any question of the form:
# "Which has more gravitational pull on a baby as it is born: the midwife, or the planet Jupiter?"

# baby ~ 5 kg
# Distance and mass of [Jupiter](http://en.wikipedia.org/wiki/Jupiter) 

gravitationalAttraction <- function(G = 6.674E-11, m1, m2, r){
  # G = 6.674E-11 # [Gravitational constant](http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation): N m^2 kg^-2
  G * (m1 * m2)/r^2
}