Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Supported by

RM ANCOVA - calculating the bayes factor

A reviewer is asking us to perform bayesian analyses to quantify strength of evidence for the null. I am new to Bayesian statistics, but luckily JASP is really straightforward! I do have some questions however. I performed a bayesian RM ANCOVA, with a within subjects factor (under the factor 'time', with 2 levels), a between subjects factor (group randomisation), and a covariate (RCQ).

My first question is, if you want to do the analyses to evaluate the strength of evidence for the null, what bayes factor do you select in the analyses; B10 or B01? For the analyses I did, I selected the B01 since I believe this gives results on how much better the data predicts the null hypothesis compared to the alternative hypothesis?

Then I wanted to calculate the bayes factor. I found an article (Bayes like a Baws: Interpreting Bayesian Repeated Measures in JASP, by Sebatiaan Mathôt) on how to calculate the Bayes (or Baws) factor when you have multiple interaction terms, but I am wondering if this is the correct way to calculate the factor.

I've added the results table below. Based on the aforementioned article, I summed all P(M|data) of the models with the interaction term and divided that by the summed P(M|data) of the 'corresponding' models without the interaction term. So in the example below I performed the following calculation:

Baws factor ((0.055 + 0.017) / ( 0.178 + 0.050)) = 0.32

But is this the correct calculation, or do I need to do it differently?

Comments

  • Hi Mieke,

    Nice to hear that you read my post :-) And yes, assuming that you're interested in the Time * randomisatie nac of place interaction, the calculation is correct. So there is evidence against this interaction.

    Cheers,
    Sebastiaan

  • Hi Sebastiaan,

    Thanks for the quick response! And for the very clear post of course! :)

    I am indeed interested in the interaction. So how do I interpret this? Originally, I performed a parametric rm ancova, and there was no significant interaction (e.g. no treatment effect on the dependent variable). So the reviewer requested bayesian analyses to see if there is evidence for the null. So no evidence that there is an effect and no evidence that there is not an effect? I'm having trouble comprehending what this means. Could you help me with this?

    Best,
    Mieke

  • There is evidence for the null, the null being the absence of an interaction in this case. So that makes perfect sense given that the interaction was non-significant in the regular ANCOVA.

    I think this may be the source of confusion:

    For the analyses I did, I selected the B01 since I believe this gives results on how much better the data predicts the null hypothesis compared to the alternative hypothesis?

    That's correct, but it only affects the columns that contain a Bayes Factor. You directly took the P(M|data), and used that to calculate your own BF10. If you wanted to have a BF01 instead, it would be:

    BawsFactor01 = ( 0.178 + 0.050) / (0.055 + 0.017) = 3.17

    Does that make sense?

  • Yes, that makes sense. I have one more question about the interpretation of the BawsFactor. In this case (BawsFactor01=3.17), can I state that there is sufficient evidence for the null hypothesis? Or otherwise, how do I report this result?

  • This is a table from Wetzels and colleagues with some rules of thumb. So I would describe it as 'substantial evidence against the existence of an interaction'. Something along those lines should be fine.

  • Thank you so much for your help, I really appreciate it!!! :D

  • For an interpretation of the strength of evidence that a Bayes factor provides, see the cartoon here: https://osf.io/3acm7/

Sign In or Register to comment.

agen judi bola , sportbook, casino, togel, number game, singapore, tangkas, basket, slot, poker, dominoqq, agen bola. Semua permainan bisa dimainkan hanya dengan 1 ID. minimal deposit 50.000 ,- bonus cashback hingga 10% , diskon togel hingga 66% bisa bermain di android dan IOS kapanpun dan dimana pun. poker , bandarq , aduq, domino qq , dominobet. Semua permainan bisa dimainkan hanya dengan 1 ID. minimal deposit 10.000 ,- bonus turnover 0.5% dan bonus referral 20%. Bonus - bonus yang dihadirkan bisa terbilang cukup tinggi dan memuaskan, anda hanya perlu memasang pada situs yang memberikan bursa pasaran terbaik yaitu http://45.77.173.118/ Bola168. Situs penyedia segala jenis permainan poker online kini semakin banyak ditemukan di Internet, salah satunya TahunQQ merupakan situs Agen Judi Domino66 Dan BandarQ Terpercaya yang mampu memberikan banyak provit bagi bettornya. Permainan Yang Di Sediakan Dewi365 Juga sangat banyak Dan menarik dan Peluang untuk memenangkan Taruhan Judi online ini juga sangat mudah . Mainkan Segera Taruhan Sportbook anda bersama Agen Judi Bola Bersama Dewi365 Kemenangan Anda Berapa pun akan Terbayarkan. Tersedia 9 macam permainan seru yang bisa kamu mainkan hanya di dalam 1 ID saja. Permainan seru yang tersedia seperti Poker, Domino QQ Dan juga BandarQ Online. Semuanya tersedia lengkap hanya di ABGQQ. Situs ABGQQ sangat mudah dimenangkan, kamu juga akan mendapatkan mega bonus dan setiap pemain berhak mendapatkan cashback mingguan. ABGQQ juga telah diakui sebagai Bandar Domino Online yang menjamin sistem FAIR PLAY disetiap permainan yang bisa dimainkan dengan deposit minimal hanya Rp.25.000. DEWI365 adalah Bandar Judi Bola Terpercaya & resmi dan terpercaya di indonesia. Situs judi bola ini menyediakan fasilitas bagi anda untuk dapat bermain memainkan permainan judi bola. Didalam situs ini memiliki berbagai permainan taruhan bola terlengkap seperti Sbobet, yang membuat DEWI365 menjadi situs judi bola terbaik dan terpercaya di Indonesia. Tentunya sebagai situs yang bertugas sebagai Bandar Poker Online pastinya akan berusaha untuk menjaga semua informasi dan keamanan yang terdapat di POKERQQ13. Kotakqq adalah situs Judi Poker Online Terpercayayang menyediakan 9 jenis permainan sakong online, dominoqq, domino99, bandarq, bandar ceme, aduq, poker online, bandar poker, balak66, perang baccarat, dan capsa susun. Dengan minimal deposit withdraw 15.000 Anda sudah bisa memainkan semua permaina pkv games di situs kami. Jackpot besar,Win rate tinggi, Fair play, PKV Games