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closeDetail requested on protocol for random assignment
Posted by aprzybylski on 19 Apr 2016 at 19:08 GMT
Greetings Drs. Gabbiadini, Riva, Andrighetto, Volpato, and Bushman. I've read this work and its coverage with great interest. Reviewing your methodology I have a question regarding how participants were assigned to condition. In the abstract you write "Participants (N = 154) were randomly assigned to play a violent-sexist game, a violent-only game, or a non-violent game..." and in the procedure section you write "...participants were randomly assigned to play a violent-sexist video game (i.e., GTA San Andreas or GTA Vice City; both rated 18+ for violent and sexual content), a violent-only video game (i.e., Half Life 1 or Half Life 2; both rated 16+ for violent action, but no sexual content or violence toward women), or a non-violent video game (i.e., Dream Pinball 3D or Q.U.B.E. 2; both rated 10+ with no violent or sexual content)." I take this to mean that you randomly assigned participants to one of three conditions (i.e. fixed factors) and they played one of two games within this factor (i.e. random factors)." Could you please elaborate, in detail, on your procedure for assignment to condition and how you selected which game a participant played within a condition. Many thanks.
RE: Detail requested on protocol for random assignment
agabbiadini replied to aprzybylski on 20 Apr 2016 at 22:16 GMT
Dear aprzybylski, thank you for your interest in our work.
For the data collection we had an agreement with one italian high school. We had 8 high school classes available for this study. If I can remember well, the data collection lasted 15/17 days. Every day we used a different game.
For example, the first day, participants planned to take part in the study in that very day played with GTA, the next day the participants planned for that day pleayed PINBALL, on the third day participants played half life... and so on.
We had no a-priori information about students who took part into the data collection. We just had the name of the class (i.e, 2A, 2B, 3A, 3B...)
RE: Detail requested on protocol for random assignment
aprzybylski replied to agabbiadini on 21 Apr 2016 at 18:06 GMT
Hello Dr. Gabbiadani,
Thank you for your prompt response to my query. If I understand you correctly this means the study you describe was a quasi-experiment wherein you assigned games to participants on the basis of their classroom (e.g. everyone in class 2A played game X). I would suggest amending the text so that readers not familiar with the structure of Italian secondary schools are not confused by the existing wording. I was unable to find a class ID variable that identifies the blocks of your randomisation; Could you direct me to this in the dataset? Browsing the spreadsheet on OSF I cannot find these values (e.g. 2A). Thank you again.
RE: RE: Detail requested on protocol for random assignment
agabbiadini replied to aprzybylski on 21 Apr 2016 at 19:01 GMT
Dear aprzybylski, I think i did not explain the randomization well...
I try to explain it better now...
For data collection the hish school insitute gave us a laboratory with 30 computers. The lab was a very large room ( at least 12 m by 8m) Participants were sent directly by their teachers to the lab into groups of 5/6 persons. We used computers very distant one from each other (at least 4 meters one from another). Each computer was divided by some plastic separators. all participants had headphones and, after an initial general introduction to the data collection, each participant read some instruction on a paper near his/her computer.
The games were randomized accross the experimental sessions.. For example, if the class 2A consisted of 18 students, then the first 6 participants played GTA San Andreas / GTA vice city, the second group of the same class played PINBALL / QUBE while the third group played Half Life 1 / Half life 2. The order of the games was randomized during the days.
We did not know the order in which the various classes were intended to participate in the study. There was a referent teacher who decided the order of the classes (ie first day -> 2A, second day 4A....)
Thus, at least 1/3 of class 2A played a violent and sexist game, 1/3 of the class played a neutral game and 1/3 payed a violent game.
There is no column for the class ID since we do not know what class arrived in the lab.
RE: Detail requested on protocol for random assignment
aprzybylski replied to agabbiadini on 22 Apr 2016 at 18:16 GMT
Hello Dr. Gabbiadani,
I appreciate you taking the time to describe the study setting and role of the participating teachers. Having collected data in school settings, I understand that field work can present logistical hurdles such as you detail. With that in mind I would suggest you amend the text to reflect the quasi-experiment you described above as it would inform those keen to understand and reproduce your work.
I have a follow-up question if it is not an imposition as I cannot figure out how the protocol ensured that each class had a 1/3 1/3 1/3 split by condition. So just so I understand it. You had each classroom (e.g. class 2A of 18 15yr. olds) come into a room at a time. Once in that room 1/3 of them randomly played a violent/sexist game (e.g. GTA), 1/3 played a violent/nonsexist game (e.g. HL) and 1/3 played a control game (Pinball). Is that correct? I could not find variables reflecting day or session in the spreadsheet. You have been generous your time, many thanks.
RE: RE: Detail requested on protocol for random assignment
agabbiadini replied to aprzybylski on 22 Apr 2016 at 20:35 GMT
No...it was not like that. Each classroom (e.g. class 2A of 18 15yr. olds) was randomly divided in three groups by their teachers. The firs group (6 persons) come into a room from 8.00 am to 9.15 am. Then the second group (6 persons) come into the lab from 10.00 to 11.15. Finally the third group (6 persons) reached the lab from 12.00 to 13.15. The firs group played sexist games. The second group played violent only games, while the third group played neutral games.
The next day we just changed the order of the games with a new class (i.e, class 4A, 18 participant, 17 years old)... for example, the first group played with neutral games, the second group played sexist games and the third group played violent-only games.
We do not know which class came to the lab, since the teachers decided which class had to take part in the data collection and in which day.
best,
Alessandro
RE: RE: Detail requested on protocol for random assignment
aprzybylski replied to agabbiadini on 25 Apr 2016 at 18:19 GMT
Dear Dr. Gabbiadini Thank you again for taking the time to provide detail on your study. As far as I can tell it does not appear that participants had 33% chance of falling into one of the three experimental conditions as you describe. Nearly all (92%) of those assigned to the sexist condition (played GTA) were either 15 or 16yrs old. I do not understand how only 4 of 84 participants over 16yrs could have been assigned to the sexist condition if participating classes were evenly divided into thirds. Indeed, 0 of 22 participants aged 15yrs played a game other than GTA.
It is possible I am missing critical information which would explain how 33% of a given class would have been assigned to each condition, but I do not believe the paper or data, in their current form, describe how this might be. Is it possible the teachers made an error? Finally, it is not clear if the subject IDs in the sheet reflect the order participants were run in and I have not been able to find variables that reflect factors you discuss such as day or session the spreadsheet. My regards.