Adjusting prior scale factor in correlations using JZS prior

Comments

• EJ

  April 2016 edited 2:44AM

  Hi Julie,

  There's nothing wrong with the WW2012 approach, but if you want to do this in JASP then you can selection "Bayesian correlation pairs" and explore different prior widths. The JASP version of the correlation test comes from Jeffreys (1961), who assigned a uniform prior on the correlation coefficient.

  Cheers,
  E.J.
• Julie

  April 2016 edited 2:44AM

  Thanks E.J. Although I have used the JZS prior for my other analyses, so for the sake of consistency is there a way to easily adjust the prior for the W&W version? I really appreciated your help.

  Julie
• EJ

  April 2016 edited 2:44AM

  Hi Julie,

  The code should specify some "r" scale value that you can change...yes, see here:
  http://www.ejwagenmakers.com/2012/BFcorrelationsLargeN.R

  Cheers,
  E.J.
• Julie

  April 2016 edited 2:44AM

  Sorry, I think I am still confused. I thought the r value in the code was representative of the correlation coefficient, not the scale factor...am I wrong? After re-reading the paper, I get the impression I should be adjusting g given that informs the prior....
  Apologies if I have it wrong. Would you mind clarifying?

  Thank you so much for your help-much appreciated!
• EJ

  April 2016 edited 2:44AM

  My bad! Yes, you are right, g informs the prior (see also http://www.ejwagenmakers.com/2012/WetzelsEtAl2012AmStat.pdf)

  Cheers,
  E.J.
• Julie

  April 2016 edited 2:44AM

  Thank you E.J. Much appreciated!