Articles by jackstat

Revisiting Cronbach 1951 via Simulation with Shiny

January 9, 2013 | jackstat

At the time of the creation of this blog, Cronbach’s 1951 piece on coefficient alpha has 18,132 citations according to google scholar.  The main use of coefficient alpha is to assess internal consistency reliability of a test or survey.   Although it may have been forgotten, the proof Cronbach demonstrated established that ... [Read more...]

Creating a Covariance Matrix from Scratch

January 7, 2013 | jackstat

I have been conducting several simulations that use a covariance matrix.  I needed to expand the code that I found in the psych package to have more than 2 latent variables (the code probably allows it but I didn’t figure it out).  I ran across Joreskog’s 1971 paper and realized ... [Read more...]

Internal Consistency Reliability in R with Lambda4

January 6, 2013 | jackstat

For the last year I have been developing a package “Lambda4” to improve internal consistency reliability estimation.  In the package’s conception my primary concern centered on H.G. Osburn’s maximized lambda4 estimator.  Despite a very thorough search I could not find a stats package that could utilized Osburn’... [Read more...]

Demonstrating Confidence Intervals with Shiny

January 6, 2013 | jackstat

For the introductory statistic student confidence intervals can seem a daunting concept to grasp.  Quite simply put it is an interval that we have a certain measure of confidence that the population parameter falls into.  The 95% confidence is the most common value chosen in my academic circle.  Nevertheless, many others ... [Read more...]

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