jzs_cor: A default Bayesian hypothesis test for correlation (Wetzels,... In BayesMed: Default Bayesian Hypothesis Tests for Correlation, Partial Correlation, and Mediation

Description

This function can be used to perform a default Bayesian hypothesis test for correlation, using a Jeffreys-Zellner-Siow prior set-up (Liang et al., 2008).

Usage

 1 2 3 jzs_cor(V1, V2, alternative = c("two.sided", "less", "greater"), n.iter=10000,n.burnin=500,standardize=TRUE)

Arguments

 V1 a numeric vector. V2 a numeric vector of the same length as V1. alternative specify the alternative hypothesis for the correlation coefficient: two.sided, greater than zero, or less than zero. n.iter number of total iterations per chain (see the package R2jags). Defaults to 10000. n.burnin length of burn in, i.e. number of iterations to discard at the beginning(see the package R2jags). Defaults to 500. standardize logical. Should the variables be standardized? Defaults to TRUE.

Details

See Wetzels & Wagenmakers (2012).

Value

The function returns a list with the following items:

 Correlation The correlation coefficient for the relation between V1 and V2. The correlation coefficient is calculated by standardizing the mean of the posterior samples: mean(samples)*(sd(V1)/sd(V2)). BayesFactor The Bayes factor for the correlation coefficient. A value greater than one indicates evidence in favor of correlation, a value smaller than one indicates evidence against correlation. PosteriorProbability The posterior probability for the existence of a correlation between V1 and V2. alpha The posterior samples for the correlation coefficient alpha. jagssamples The JAGS output for the MCMC estimation of the path. This object can be used to construct a traceplot.

Author(s)

Michele B. Nuijten <m.b.nuijten@uvt.nl>, Ruud Wetzels, Dora Matzke, Conor V. Dolan, and Eric-Jan Wagenmakers.

References

Liang, F., Paulo, R., Molina, G., Clyde, M. A., & Berger, J. O. (2008). Mixtures of g priors for Bayesian variable selection. Journal of the American Statistical Association, 103(481), 410-423.

Nuijten, M. B., Wetzels, R., Matzke, D., Dolan, C. V., & Wagenmakers, E.-J. (2014). A default Bayesian hypothesis test for mediation. Behavior Research Methods. doi: 10.3758/s13428-014-0470-2

Wetzels, R., & Wagenmakers, E.-J. (2012). A Default Bayesian Hypothesis Test for Correlations and Partial Correlations. Psychonomic Bulletin & Review, 19, 1057-1064.