d-Score calculation

[Ursula Meidert]

Hi there,
I conducted a IAT on homosexuality/heterosexuality using the examles on minotask on github. In the CSV output with the raw data is a d-score listed. I tried to caltulate the d-score by hand to doulbe-check if it is correct as I'm a bit puzzled by the overall results. Could you please tell me 1. where I can find/look at the code for the calculaton (I was not able to finde it) and 2. tell me which  version for the calculation was used? I was following the improved version by Greenwald which I found on SoSci (https://www.soscisurvey.de/help/doku.php/en:create:questions:iat). If I use his formula I get a slightly different figure than the score in the file. I would really like to resolve this. 
Thank you very much in advance for your advice.
Ursula

[Yoav Bar-Anan]

Hi Ursula, 

The D score computed by the scorer is almost identical to D2 from Greenwald et al.'s 2003 (see Table 2). The main difference is that instead of computing D1 from Blocks 3 and 6 and D2 from Blocks 4 and 7, we compute one D directly from Blocks 3&4 vs. Blocks 6&7. We did that for technical reasons (the scoring code is awful and I could not make it compute a score from separate parcels [I rewrote that code and it will be integrated into Minno's IAT in a few weeks]), but it turns out that it is also recommended (Richetin et al., 2015). In addition, I think that it does not compute a score if the error-rate is above 40% (unlike the recommended algorithms). If your score has around .9 correlation with the recorded D score, then you're probably computing your score correctly. You can also double-check your scoring by using the IAT R package (there are other packages, but I do not have experience with them). 

All the best,

Yoav