Bayes analysis for a linear trend.

Comments

• EJ

  June 2016 edited 9:03AM

  Hi Zennie,

  JASP does not do contrasts yet, but I think you should be able to compute what you want using Richard's BF package. I recall Richard also wrote a blogpost on this. Richard may be able to provide the details.

  Cheers,
  E.J.
• richarddmorey

  June 2016 edited 9:03AM

  "I predict that reaction times will not increase as the object size increases (a linear trend)"

  Is the alternative really a linear increase? The first part of your hypothesis suggests an unstructured alternative (and do you mean average RT?), but you've couched it as a question about a linear trend. Are you sure that the linear trend is what you want to test, and not an ordinal hypothesis (eg, X1>X2>X3)?
• zennie

  June 2016 edited 9:03AM

  Thank you both.
  Yes, I am sure that I want to test for a linear trend. As H1 states that the data should act linearly, H0 should be the lack of such trend.

  Secondly, I am thinking that I can get away with a Bayesian linear regression. Can I use the RT data as the dependent variable, and the object size as the predictor and calculate the Bayes factor for the linear regression? A high BF(01) should indicate a high probability that the data does not align linearly. If not, why is it different from calculating a linear trend using contrasts?

  Thank you again.
• richarddmorey

  June 2016 edited 9:03AM

  You can create the contrasts you want and define them as predictors, then use lmBF to test them.