Author's response to reviews

Author's response to reviews Title: Massively Multiplayer Online RolePlaying Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population Authors: Sophia Achab (Sophia.Arigo@hcuge.ch) Magali Nicolier (mnicolier@chu-besancon.fr) Frédéric Mauny (frederic.mauny@univ-fcomte.fr) Julie Monnin (jmonnin@chu-besancon.fr) Benoit Trojak (benoit.trojak@chu-dijon.fr) Pierre Vandel (pierre.vandel@univ-fcomte.fr) Daniel Sechter (daniel.sechter@univ-fcomte.fr) Philip Gorwood (p.gorwood@ch-sainte-anne.fr) Emmanuel Haffen (emmanuel.haffen@univ-fcomte.fr) Version: 9 Date: 20 August 2011 Author's response to reviews: see over

Author's response to Editorial Production Team Title: Massively Multiplayer Online RolePlaying Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population Authors: Sophia Achab (Sophia.Achab@hcuge.ch) Magali Nicolier (mnicolier@chu-besancon.fr) Frédéric Mauny (frederic.mauny@univ-fcomte.fr) Julie Monnin (jmonnin@chu-besancon.fr) Benoit Trojak (benoit.trojak@chu-dijon.fr) Pierre Vandel (pierre.vandel@univ-fcomte.fr) Daniel Sechter (daniel.sechter@univ-fcomte.fr) Philip Gorwood (p.gorwood@ch-sainte-anne.fr) Emmanuel Haffen (emmanuel.haffen@univ-fcomte.fr) Version: 8 Date: 20 th august 2011 1

Responses to BMC Editorial Production Team Please find below the responses and modifications to the comments of the editorial production team. Formatting changes to be made: ----------------------------- Major revisions (we require the author to make these changes) 1.References: Please cite references in order. At the moment, reference 5 is cited before reference 4. Can you please rearrange so these are cited in numerical order. References were reformatted. 2.References: Please provide functioning links to:- http://wwwdsm5org/newsroom/documents/addiction%20release%20final%20205 http://wwwdsm5org/newsroom/ While trying to retrieve the URL: http://www.wwwdsm5org.com/newsroom/documents/addiction%20release%20final%2020 5 The following error was encountered: unable to determine IP address from host name for www.wwwdsm5org.com. The dnsserver returned: Name Error: The domain name does not exist. Minor revisions (we can make these changes for you, although it will speed up publication of your manuscript if you do them while making the major changes above) Typography: Please take this opportunity to check your manuscript for any typographical errors and to make any final corrections or revisions. This is the final proofing stage for your manuscript, and you will not be able to make any changes after acceptance. 2

Version: 7 Date: 19 th august 2011 Formatting changes to be made: ----------------------------- Major revisions (we require the author to make these changes) 1.References: Please provide functioning link to http://wwwdsm5org/newsroom/documents/addiction%20release%20final%20205 http://wwwdsm5org/newsroom/ We are sorry but the links are not accessible. 2.References: Please make sure references are cited in numerical order. Currently, references 33 and 34 are cited after 35 and 36. We verified all references in the text. There were reformatted. We are sorry for this mistake. 3.Additional files: There are no additional files but an additional file is cited in the manuscript. Please either add the relevant file, along with a title and description of the file, or remove citations. Citations were removed. Minor revisions (we can make these changes for you, although it will speed up publication of your manuscript if you do them while making the major changes above) Typography: Please take this opportunity to check your manuscript for any typographical errors and to make any final corrections or revisions. This is the final proofing stage for your manuscript, and you will not be able to make any changes after acceptance. We corrected all typographical errors in the final version of the text file. Thank you Dear Editor, 3

Thank you very much to have agreed to publish our manuscript entitled «Massively Multiplayer Online Role Playing Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population». Responses to BMC Editorial Production Team Please find below the responses and modifications (point by point) to the comments of the editorial production team. Formatting changes to be made: ----------------------------- Major revisions (we require the author to make these changes) 1.References: Please make sure references are cited in numerical order Response to comment 1. We verified all references in the text. 2.References: please provide a functioning link to the following websites http://wwwdsm5org/newsroom/documents/addiction%20release%20final%20205 pdf http://wwwdsm5org/newsroom/ Response to comment 2. It was not possible to provide a functioning link to these websites: error message. 3.Tables: you have uploaded the tables as figure files. Please remove them from the submission system and include the tables within the text file of the manuscript following the references. The tables should not be embedded images or drawings and should be formatted from cells, not tabbed text. Please also move the table title to above the table and the legend to below the table, within the text Response to comment 3. Tables were included in the test file. All tables were reformatted. We also move the table title to above the table and the legend to below the table, within the text every time it was necessary. 4.Additional files: all additional files must be mentioned in the text in numerical order, or removed from the system Additional files: please add a section titled "Additional files" at the end of the manuscript (after the tables) listing the following for each file: the title of the data, and a short description of the data. An example is given below: Additional files Additional file 1 Title: A title to explain what is in the file. Description: A description of what the file contains. Additional file 2 Title: A title to explain what is in the file. 4

Description: A description of what the file contains. Response to comment 4. We remove all additional data. It was essentially intended for the reviewers. They remain naturally available. Minor revisions (we can make these changes for you, although it will speed up publication of your manuscript if you do them while making the major changes above) Layout: Please change your page layout from landscape to portrait Line numbers: Please remove these Headers: Please remove the header "Achab et al - revised" Author list: Please place your superscript links to the affiliations in numerical order Abbreviations: Please format these in to a paragraph. Please make sure all abbreviations are spelt out and occur in alphabetical order. Authors contributions: please ensure this is formatted into a paragraph rather than a list or in bullet points. Tables- please remove the visible vertical lines from your tables Tables: please note that we are unable to correctly display merged cells where the merged cell crosses rows: please re-layout your table without these merged elements Additional files: if any figures or tables in the additional files are mentioned within the main text and additional file section please refer to them as Additional file 1, Table S1, Additional file 1, Table S2 or Additional file 1, Figure S1, as Additional file 1, Figure S2. This will avoid confusion with any figures and tables that are included within the main text. Typography: Please take this opportunity to check your manuscript for any typographical errors and to make any final corrections or revisions. This is the final proofing stage for your manuscript, and you will not be able to make any changes after acceptance. Response to minor revisions Your comments had been taken into consideration; and all errors have been corrected. In particular all the tables were modified with correct merged cells. We corrected all typographical errors in the final version of the text file. Thank you for your consideration. Author's response to reviews: see over Version: 5 Date: 14 th july 2011 5

Dear Editor, Thank you very much for reconsidering our manuscript entitled «Massively Multiplayer Online Role Playing Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population». - Editor s comment The authors should be invited to respond to the reviewers' comments with a minor revision. Response to comment We have presented more clearly the replies to all the comments raised by the three reviewers, including minor revisions. Please find below the responses and modifications (point by point) to the reviewers comments. - Other editorial requirements Box: Unfortunately we cannot incorporate boxes. Please either change the box to a table and update any references to within the text, or include the information within the manuscript text. You can use indentation to highlight the text. Response to editorial requirements We have changed the boxes to tables as presented in a Tables separate file. Reference to tables has not changed, and each table could be presented in the edited article besides the text where it is referred to for the first time in the manuscript. Reviewer: Chih-Hung Ko Dear reviewer, thank you very much for considering our manuscript entitled «Massively Multiplayer Online Roleplaying games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population». We thank you for your positive comments. Reviewer's report: The article had provide the important information for Internet addiction. Further, the author had developed a screen tool for internet addiction. Level of interest: An article of importance in its field Quality of written English: Acceptable Statistical review: Yes, but I do not feel adequately qualified to assess the statistics. Declaration of competing interests: I declare that I have no competing interests 6

Reviewer: Matthew Brown Dear reviewer, thank you very much for considering our manuscript entitled «Massively Multiplayer Online Roleplaying Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population». Thank you for your comments. Please find below the responses and modifications (point by point) to your comments. General comments The revised manuscript is an improvement over the original. It is now clear what raw questionnaire data the authors collected and how they classified participants based on that data. Unfortunately, it is my assessment that the statistical analysis is flawed. There seems to be confusion on the nature and importance of multiple comparison and correcting for them. I discuss this in one of my comments below. For this reason, I am not convinced by the manuscript in its current form. I would like to note that the results presented in the tables do look promising, and they might in fact survive multiple comparisons correction. I encourage the authors to look into this issue in more detail. With kind regards Matthew Brown Response to general comments The statistical analysis was reconsidered particularly for multivariate statistical tests. Based on the instructions from BioMed Central, my individual comments are labelled as: (DR) Discretionary Revisions (which are recommendations for improvement but which the author can choose to ignore) (MER) Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author can be trusted to correct) (MCR) Major Compulsory Revisions (which the author must respond to before a decision on publication can be reached) 1. (MCR) Statistical tests are still not described adequately. For example, what are the details of the multivariate statistical model that was used to adjust for age, gender, and education level? For example, was this model applied to all of the various dependent variables (questionnaire items) that you measured simultaneously? Or was it applied to individual dependent variables with addiction risk positive/negative status, age, gender, and education level used as predictors? Response to comment 1. Statistical analysis section was re-written, taking your comments into consideration. In fact, all variables were adjusted (step by step) by taking into account usual factors of confusion as gender, age and socio-economic characteristics (references: 13, 14, 16, 32, 33). There is a single explained dependant variable: DAS+; but not the items of the questionnaire. DAS considered all items with a cut-off score: DAS+/DAS-. For the multivariate analysis: all variables were tested one by one independently one of the others. 2. (MCR) The issue of multiple comparisons has to be addressed here. In your reply to my original comments, you state "DAS variable was the only one main criteria. Testing the difference between 3 or more groups implies to use a specific statistical strategy including first a global test, and after 2-2 tests, and a correction of the p-value threshold. Although numerous statistic tests were conducted, in our point of view, our analysis was not concerned by a multiple comparisons situation." Multiple comparisons are a problem 7

whenever you are doing more than one test. If you do 20 separate T-tests with false positive rate controlled at p < 0.05 for the individual tests, across all 20 tests you are controlling the false positive rate at p < 1 (because 20 * 0.05 = 1). I.e., you are basically certain to observe a false positive in one of the tests. Doing multiple tests between 3 or more groups is one way to create a multiple comparison situation, as you say. However, one can also do multiple comparisons when measuring multiple dependent variables from two different groups (addiction risk positive and negative groups), as you are doing here. Given that you are performing around two dozen univariate statistical tests, some kind of multiple comparison correction is necessary. One simple though severe correction is the Bonferroni correction, in which you simply multiply each univariate test's p-value by the number of tests you are performing. The univariate tests look promising. Many of the test statistic values (eg: chisquared values) are quite high. These tests might well survive a Bonferroni correction, not to mention a less conservative multiple comparison correction. Response to comment 2. We made adjustments related to multiple comparisons. Bonferroni correction is the most popular of the methodologies controlling the increase of false positive rate in Multiple Comparison Procedure (MCP). It aims to control the probability of committing any type I error in comparisons under simultaneous consideration (the family wise error rate or FWER). But this procedure is also the most conservative correction, drastically reducing the power of the analyses. So, we applied an alternative approach proposed by Benjamini and Hochberg [Benjamini et al.,1995], which is controlling the expected proportion of falsely rejected hypotheses, the False Discovery Rate (FDR). This correction was applied to groups of simultaneous tests of null hypotheses. Analyses were considered as simultaneous when the independent variables were describing a characteristic of the same family, and were presented in the same tables. (MMORPG addiction s screening scales, baseline demographics, and social impairments ). Corrected p-values [Reiner, 2003] and corrected Confidence Intervals [Benjamini et al., 2005] were calculated in order to control FDR (tables have been revised). Benjamini Y. and Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple testing. 1995; J. R. Statist. Soc. B. Vol. 57: 289-300. Benjamini Y. and Yekutieli D. False Discovery Rate: Adjusted Multiple Confidence Intervals for Selected Parameters. Journal of the American Statistical Association, 2005; 100, vol 46971-81. 3. (MCR) In addition, your univariate tests are not independent from each other. For example, the same individuals who reported having financial difficulties likely also reported marital problems as well as other problems. Therefore, significance or non-significance on one test will tend to be associated with significance or non-significance in other tests. Response to comment 3. We made adjustments related to univariate tests. 4. (DR) The manuscript was difficult to read. Details of statistics (p values, computed statistics values, degrees of freedom, which test was used) are not included in the text of the Results section, though some of these details are included in the Tables. This originally obscured the fact that several of the differences you stated to have observed in your data were not in fact significant. Only careful comparison of the Tables with the Results text revealed this. Having to flip back and forth between the Results text and the Tables was also distracting. Response to comment 4. 8

Your comment had been taken into consideration; details of statistics were included in the text. Unfortunately, we mentioned two confusing variables in the text that are not significant (age and gender, table 3). 5. (DR) There are several typographical errors throughout the text. Response to comment 5. Your comment had been taken into consideration, and typographical errors have been corrected. 6. (MER) pdf p3 "The 453 participating adult gamers were young adult graduates living alone in urban areas.": The participants were living alone even though some of them reported marital and / or family difficulties? Response to comment 6. The 453 participating adult gamers were mainly young adult graduates living alone in urban areas. The sentence was corrected in the text. 7. (MER) pdf p5 "This distinction is sustained by recent neurobiological findings on the different neuronal process involved in dependence or addiction.": Provide reference(s) to support this statement. Response to comment 7. Thank you for your comment, the reference below has been provided in the text. Everitt BJ, Belin D, Economidou D, et al. Review. Neural mechanisms underlying the vulnerability to develop compulsive drug-seeking habits and addiction. Philos Trans R Soc Lond B Biol Sci. 2008; 363:3125 3135. 8. (MER) pdf p13 Statistical Analysis: Much necessary information is missing here. For example, you mention that some specific univariate tests were used in "Univariate analysis was performed using the two-sample t-test (continuous variables), Pearson s chi-square test (unmatched categorical variables)." But, you do not specify which data these tests were used on, which comparisons were being made, and so on. I am having to flip back and forth among the Methods, Results, and Tables to try to figure out what comparisons you made. Most readers will not be as patient, which will reduce your paper's impact. I have similar concerns for the other tests you mention here. Response to comment 8. Statistical analysis section was re-written, taking your comments into consideration. 9. (DR) pdf p14-16 Results: P-values and other statistical test details are not in the text, though you do reference Tables with this information. You do not even state that a given observation is statistically significant (or not significant). This forces me to break my train of reading to go look up a table just to be sure that a stated difference is actually significant and at what level. This makes your results harder to read. Response to comment 9. The results section has been re-written, taking your comments into consideration. 10. (DR) pdf p15 "DAS was statistically associated with GIAD and ISS (all p<10-3 )": I originally thought you had done some kind of multivariate test to show an overall statistical 9

association, but later I figured out that you were merely introducing the univariate tests which you discuss next. You might want to clarify this for your readers. Response to comment 10. DAS was statistically associated on one hand with GIAD and on the other hand with ISS (respectively p<10-3 and p<10-3 ). 11. (MER) pdf p15 "77.5% (84+263 on 448) of concordant responses were found for the 355 DAS and ISS scales." What do the (84+263) numbers mean? What does "concordant responses" mean? Does this mean that 77.5% of participants were classified the same with respect to addiction in the DAS and ISS scales (i.e. 77.5% of participants were classified either as not addicted on both the DAS and ISS or as addicted on both the DAS and ISS)? Response to comment 11. This section has been rephrased to improve reader s understanding as you suggested. 12. (DR) pdf p15 "Similar results were observed regardless of the scales studied (See appendix tables for results obtained with ISS and GIAD scales)." This sentence is imprecise, and I'm not sure of your point here. Results were similar in what way? Response to comment 12. The sentence was re-written following your recommendation. 13. (MER) pdf p15-p16 (line 372-375): In the text, you fail to mention that the differences between the DAS+ and DAS- groups in terms of age and gender composition were not significant. This is only evident through careful cross-referencing with Table 3. You need to include details of p values, computed statistics, statistics tests, and degrees of freedom in the results text. Even if this means presenting that information twice (in the text and in the tables), this is acceptable as the emphasis should be on clarity and ease of reading. Response to comment 13. We agree with your comment. The results section has been re-written to provide more details. 14. (MER) pdf p17 line 414: There is a crucial word missing in this sentence: "GREATER in game sense of power". Response to comment 14. Your comment had been taken in consideration and we rephrased this part of the manuscript. 15. (MER) Tables: The "Crude monovariate statistical test" phrase is unclear. This term is not used in the Methods section. I assume this refers to the chi-squared and t-tests. Using inconsistent terminology places an unnecessary extra burden on the reader. Response to comment 15. We have clarified the tables content. 16. (MER) Tables: What is the "multivariate adjusted #"? 10

Response to comment 16. We have clarified the table 7 content: multivariate analysis; # = odd ratio and p value were adjusted for age, sex and educational level. 17. (MER) Tables: I do not see degrees of freedom stated anywhere for the tests described. Response to comment 17. Degrees of freedom were added, taking your comments into consideration. Level of interest: An article whose findings are important to those with closely related research interests Quality of written English: Acceptable Statistical review: Yes, and I have assessed the statistics in my report. Declaration of competing interests: I declare that I have no competing interests. 11

Reviewer: Dave Hayes Dear reviewer, thank you very much for considering our manuscript entitled «Massively Multiplayer Online RolePlaying Games: Comparing characteristics of addict vs non-addict online recruited gamers in a French adult population». Thank you for your comments. Please find below the responses and modifications (point by point) to your comments. Reviewer's report: While the authors have sufficiently answered most of my questions, there are still a number of related concerns. My main concern is that it seems that the results are still overstated, or are unclear, in many instances. In addition, I have the following comments/questions: Comment - Line 111-12: Are tolerance, withdrawal etc really disorders? Response to comment The word disorder has been replaced in the text by symptoms that is effectively much pertinent. Comment - I m still skeptical about the use of addiction or dependence for gaming behaviour, though I recognize that there are many shared facets. Despite the additional text in the introduction, I must admit I m not entirely clear on precisely how the authors are using these terms though it seems that they are reserving dependence for physical dependence and addiction for the broader behavioural aspects. If so, this would be fine for the present study, however, it should be emphasized that a clear characterization of abhorrent gaming behaviour (and it s connection, if any, to addiction) is still under review and is thus debatable. Response to comment We thank you for your appreciation on the clarification on the use of both concepts dependence and addiction. In this study we followed the recent tendency to use the term dependence for physical dependence and the term addiction for loss of control, automatism, and the persistence of the behaviour despite the adverse consequences (Balland and Lüscher, 2009). We completely agree with you that there is no clear characterization yet of abhorrent gaming behaviour, even if scientific community refers to it in a growing number of publications as a part of behavioural addictions (Grant et al. 2010). Its acceptance as a disorder and then as an addictive disorder is effectively yet to come (APA, 2010). Balland B, Lüscher C: L'addiction : lorsque l'emballement des mécanismes d'apprentissage conduit à la perte du libre arbitre. Psychiatr Sci Hum Neurosci 2009, 7:35-42. Grant JE, Potenza MN, Weinstein A, Gorelick DA: Introduction to behavioural addictions. Am J Drug Alcohol Abuse 2010, 36:233-241. A.P.A.: DSM-5 Proposed Revisions Include New Category of Addiction and Related Disorders. New Category of Behavioural Addictions Also Proposed. Washington, DC: American Psychiatric Association Available at http://wwwdsm5org/newsroom/documents/addiction%20release%20final%20205pdf 2010, News Release. 12

Comment - Line 539: I suspect that the higher rates for IA reported here (compared to other literature) may be due to Type I errors related to the many limitations of this study again, I think it would benefit to point this out. Response to comment We agree with you in this point. Comment - The manuscript still needs to be corrected for appropriate English grammar and minor errors (e.g. lines 277-280: How does playing make you feel? and grated should be greater and fell should be felt). There are many errors such as these, and they often prevent the reader from having a clear understanding of what the authors mean. Response to comment We apologize for the English grammar and the typographical errors, the whole article has been corrected. - Level of interest: An article whose findings are important to those with closely related research interests - Quality of written English: Needs some language corrections before being published Language corrections have been made. - Statistical review: Yes, and I have assessed the statistics in my report. Declaration of competing interests: 'I declare that I have no competing interests' 13