JohnnyB

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• Hi Anna, Great to hear! It's certainly possible to obtain evidence in favor of an effect, even though it's small, most commonly if you have a large data set - is that the case for you? I like playing around in the summary statistics module to get so…

  in 95% Credibility Intervals for Bayesian ANCOVA Comment by JohnnyB June 22
• Hi Martin, Do you have a JASP file I could take a look at? I don't think anything has changed there, but it might be that a default option has changed, for instance using the standard error instead of the confidence intervals, or maybe whether to av…

  in RM ANOVA 95% CI Comment by JohnnyB June 16
• Hi Gaspar, 1) Yes, the R-code is limited that way, in that it only does the two-sided tests. 2) The giveBAyesFactorZeroOne is the same for both the rank sum and signed rank test, since it applies the Savage-Dickey density ratio (i.e., the ratio of …

  in Bayes Factors for non-parametric tests Comment by JohnnyB June 5
• Hi Statisticum, Which test are you running in SPSS and Simstat? Do these programs give the Z value by default for the wilcoxon signed rank test? In any case, I checked the data in R, and the wilcox.test gives the same result as JASP for paired obs…

  in Wilcoxon signed ranked test Comment by JohnnyB May 13
• Hi Baba, How much memory (RAM) does your computer have, and is your task manager showing you are running at 100% RAM? Such an error message is thrown by R whenever it cannot obtain enough RAM for its objects. I have seen this error before with very…

  in "Cannot allocate vector of size 3.1 Gb" on Repeated M. ANOVA Comment by JohnnyB May 3
• Hi Eniseg, For help on interpretation, the following figure from one of our guidelines papers can be helpful (scroll down to the third figure and caption: https://www.researchgate.net/publication/330569075_The_JASP_Guidelines_for_Conducting_and_Rep…

  in Mann-Whitney W in JASP, isn't it usually a U? Comment by JohnnyB April 29
• Hi Mila, In the Bayesian ANOVA, these terms have a bit of a different meaning - this is from the JASP help file: Fixed Factors: The variables that are manipulated/define the different groups. These are also called the independent variables. Random …

  in ANOVA with random factor Comment by JohnnyB April 27
• Thanks KB, that's great to hear!

  in Help for covariate analysis with Mixed ANOVA Comment by JohnnyB April 21
• Hi, It seems that in the descriptives table, Claarek specified the descriptives of Age, split by another variable that has the levels 0 and 1 (the table does not show which variable that is, maybe that is good to add to JASP so the table becomes mo…

  in Mixed repeated measures ANOVA with covariate Comment by JohnnyB April 19
• Hi Eniseg2, As DrMark pointed out, the history of the test is a little complicated, leading to different naming conventions of both the test itself (Wikipedia already lists 4 names) and the test statistic (U or W). For the test statistics, this is …

  in Mann-Whitney W in JASP, isn't it usually a U? Comment by JohnnyB April 18
• Hi Kev_bague, There is no covariate box in the ANOVA, only in the ANCOVA - which is the difference between the two analyses: in the underlying code, the ANOVA just calls the code of ANCOVA but supplies a model without covariates (this is not JASP s…

  in Help for covariate analysis with Mixed ANOVA Comment by JohnnyB April 18
• Hi Eniseg, In order to get the posterior estimates per model, you can specify your desired model under the section "single model inference". There, you can specify the model (e.g., the best model according to the model comparison table), …

  in 95% Credibility Intervals for Bayesian ANCOVA Comment by JohnnyB April 18
• Hi Rohanp, Ah yes that makes life a lot easier! In that case you can do the subsetting and ANOVA in R. JASP indeed uses the BayesFactor package for the Bayesian ANOVA's. Here you can read more about using BayesFactor: https://cran.r-project.org/web…

  in Following up an interaction in Bayesian RM ANOVA Comment by JohnnyB April 14
• Hi rohanp16, The simple main effects analysis is essentially running ANOVA's for different subset of the data (conditioning on each level of the "moderator variable"). In the frequentist ANOVA this is automated for you, but unfortunately t…

  in Following up an interaction in Bayesian RM ANOVA Comment by JohnnyB April 13
• Hi Hfac, I looked at our dataset, and because you included the interaction term education x income, there need to be at least 2 observations per cell. If you look at "Descriptives", then select one variable, select the other variable as t…

  in Error: "There are aliased coefficients in the model" for an ANOVA Comment by JohnnyB April 7
• Hi Nathalie, That's how the emmeans works: it operates based on the model you specify. In the ANOVA model, there is the assumption of equal variances, so that influences how emmeans handles the pairwise comparisons. We offer a workaround, where (fo…

  in Pooled errror term for RM factor for posthoc tests Comment by JohnnyB March 24
• Hi HMSTAT, The Chi squared is the original test statistic as proposed by Durbin, whereas the F statistics is a slight variation on it, introduced later. (see https://en.wikipedia.org/wiki/Durbin_test#Test_definition for the history). For completenes…

  in Durbin Test - non-parametric mixed ANOVA Comment by JohnnyB March 4
• Hi Ataylor4, The marginal means are calculated in a different way from the descriptives. The descriptive means are simply based on just the observations, whereas the marginal means are an estimation of what the means would be, in case the design wou…

  in Marginal Means vs Descriptives Comment by JohnnyB March 1
• Hi Nathalie, That's a good point - we use the emmeans package for most of the posthoc/marginal means/contrast computations, but in order to use the unpooled error term, we do these computations manually. The R code that JASP uses takes the observat…

  in Pooled errror term for RM factor for posthoc tests Comment by JohnnyB February 18
• Hi JLeborgne, For these tests, the df is equal to n - 1 (as with the paired samples t-test), I will look into adding these to the JASP output - great suggestion! Cheers, Johnny

  in RM ANOVA Post hoc comparisons - degrees of freedom? Comment by JohnnyB February 16
• Hi JLeborgne, In essence, the analysis is indeed running paired samples t-tests. We use the emmeans package for this in R. Are you assuming equal variances or not? Maybe that is causing the different results. JASP offers both options (equal varianc…

  in RM ANOVA - Post hoc Bonferroni comparison? Comment by JohnnyB February 16
• Hi Elnino, What error message are you getting? The only R package you need installed is the logspline package - you can install it with install.packages("logspline"). After that all code should run. If you have any additional questions abo…

  in Bayes Factors for non-parametric tests Comment by JohnnyB February 16
• Hi AMa, JASP uses the emmeans/lsmeans package to compute the posthoc results: We first create a reference grid and estimate the marginal means with the lsmeans function by providing the ANOVA model and which factors to use for post hoc tests. Then w…

  in ANOVA post-hoc t-value calculation Comment by JohnnyB February 3
• Hi mcp, I think that error is not just concerning the Kruskal Wallis test, but the overall ANOVA. It seems that you only have a single observation per cell of the interaction effect, so when you include that effect, there is no way of calculating th…

  in kruskall-wallis analysis problem Comment by JohnnyB February 3
• Hi, Apologies for the late reply, and thanks for your insightful post. You are right that we use the MBESS package for computing the confidence intervals around the effect sizes. We do this as follows: unlist(conf.limits.nct(ncp = -0.072947, 59)[c(…

  in What denominator does the Cohen's d use on JASP?? Comment by JohnnyB January 6
• Yes! I was waiting till all the internal JAPS rewrites were done, which almost seems to be the case. Implementing the Bayesian Spearman's rho and one-sample Wilcoxon tests is at the top of my JASP todo list =)

  in Spearman's correlation Comment by JohnnyB December 2019
• Hi Charles, Yes, the robust MAD is ran with the constant set to the default option of the MAD function. For the regular MAD, we run the same function but specify the constant to be equal to 1. Cheers, Johnny

  in MAD and MAD robust Comment by JohnnyB October 2019
• Hi Lior, This is an excerpt from our Bayesian guidelines article (https://psyarxiv.com/yqxfr), where we discuss the error percentage for ANOVA: "For some analyses, the results are based on a numerical algorithm, such as Markov chain Monte Carlo…

  in interpreting error percentage Comment by JohnnyB September 2019
• Hi Edwin, Could you specify whether you used the Bayesian ANOVA or the frequentist ANOVA? Then we can narrow down the search to where this issue might be coming from! Kind regards, Johnny

  in Why are JASP files so big? Comment by JohnnyB September 2019
• Hi Cames, For the nonparametric ANOVA, when specifying a grouping factor, it needs to be at least an incomplete balanced design in order to run the Friedman or Durbin test. Such a design has the following properties (see https://en.wikipedia.org/wik…

  in Discrepancy between Bayesian and Frequentist Repeated Measures ANOVA Comment by JohnnyB August 2019
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