Characterization and Modeling of Deleted Questions on Stack Overflow

Transcription

1 Characterization and Modeling of Deleted Questions on Stack Overflow Denzil Correa, Ashish Sureka February 16, 2014 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

2 Table of Contents Outline 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

3 Table of Contents Introduction 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

4 Introduction Research Motivation and Aim Research Motivation and Aim Stack Exchange A platform to deploy topic-based community powered Q&A websites 107 Q&A sites on diverse topics like code review, parenting, bicycles and audio-video production Stack Overflow is the first and most popular Stack Exchange website which caters to professional programmers and programming enthusiasts Users earn reputation points which is a reflection of their contribution worth to the Stack Overflow community Community based voting process to reward(or penalize) reputation of users based on question and answer quality Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

5 Introduction Research Motivation and Aim Research Motivation and Aim Stack Exchange A platform to deploy topic-based community powered Q&A websites 107 Q&A sites on diverse topics like code review, parenting, bicycles and audio-video production Stack Overflow is the first and most popular Stack Exchange website which caters to professional programmers and programming enthusiasts Users earn reputation points which is a reflection of their contribution worth to the Stack Overflow community Community based voting process to reward(or penalize) reputation of users based on question and answer quality Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

6 Introduction Research Motivation and Aim Research Motivation and Aim Stack Exchange A platform to deploy topic-based community powered Q&A websites 107 Q&A sites on diverse topics like code review, parenting, bicycles and audio-video production Stack Overflow is the first and most popular Stack Exchange website which caters to professional programmers and programming enthusiasts Users earn reputation points which is a reflection of their contribution worth to the Stack Overflow community Community based voting process to reward(or penalize) reputation of users based on question and answer quality Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

7 Introduction Research Motivation and Aim Research Motivation and Aim Stack Exchange A platform to deploy topic-based community powered Q&A websites 107 Q&A sites on diverse topics like code review, parenting, bicycles and audio-video production Stack Overflow is the first and most popular Stack Exchange website which caters to professional programmers and programming enthusiasts Users earn reputation points which is a reflection of their contribution worth to the Stack Overflow community Community based voting process to reward(or penalize) reputation of users based on question and answer quality Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

8 Introduction Research Motivation and Aim Research Motivation and Aim Stack Exchange A platform to deploy topic-based community powered Q&A websites 107 Q&A sites on diverse topics like code review, parenting, bicycles and audio-video production Stack Overflow is the first and most popular Stack Exchange website which caters to professional programmers and programming enthusiasts Users earn reputation points which is a reflection of their contribution worth to the Stack Overflow community Community based voting process to reward(or penalize) reputation of users based on question and answer quality Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

9 Introduction Research Motivation and Aim Research Motivation and Aim Stack Overflow is a free, open website to all Internet users Community would like to ensure minimal possible noise on the website Questions which are very poor in quality or extremely off topic in nature are deleted from the website. Phenomena of deleted questions on Stack Overflow to gain insights about the nature of poor quality questions A deleted question is a direct feedback to the question asker that her question is poor A system to predict deleted questions would help both the users and community moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

10 Introduction Research Motivation and Aim Research Motivation and Aim Stack Overflow is a free, open website to all Internet users Community would like to ensure minimal possible noise on the website Questions which are very poor in quality or extremely off topic in nature are deleted from the website. Phenomena of deleted questions on Stack Overflow to gain insights about the nature of poor quality questions A deleted question is a direct feedback to the question asker that her question is poor A system to predict deleted questions would help both the users and community moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

11 Introduction Research Motivation and Aim Research Motivation and Aim Stack Overflow is a free, open website to all Internet users Community would like to ensure minimal possible noise on the website Questions which are very poor in quality or extremely off topic in nature are deleted from the website. Phenomena of deleted questions on Stack Overflow to gain insights about the nature of poor quality questions A deleted question is a direct feedback to the question asker that her question is poor A system to predict deleted questions would help both the users and community moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

12 Introduction Research Motivation and Aim Research Motivation and Aim Stack Overflow is a free, open website to all Internet users Community would like to ensure minimal possible noise on the website Questions which are very poor in quality or extremely off topic in nature are deleted from the website. Phenomena of deleted questions on Stack Overflow to gain insights about the nature of poor quality questions A deleted question is a direct feedback to the question asker that her question is poor A system to predict deleted questions would help both the users and community moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

13 Introduction Research Motivation and Aim Research Motivation and Aim Stack Overflow is a free, open website to all Internet users Community would like to ensure minimal possible noise on the website Questions which are very poor in quality or extremely off topic in nature are deleted from the website. Phenomena of deleted questions on Stack Overflow to gain insights about the nature of poor quality questions A deleted question is a direct feedback to the question asker that her question is poor A system to predict deleted questions would help both the users and community moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

14 Introduction Outline of Contributions, Results Research Contributions 1 We present the first characterization study of deleted questions on Stack Overflow posted over 5 years 2 Longitudinal study of deleted questions, community voting patterns, deletion behavior by question owners and discover question quality structure 3 We build a predictive model for deleted question prediction Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

15 Introduction Outline of Contributions, Results Research Contributions 1 We present the first characterization study of deleted questions on Stack Overflow posted over 5 years 2 Longitudinal study of deleted questions, community voting patterns, deletion behavior by question owners and discover question quality structure 3 We build a predictive model for deleted question prediction Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

16 Introduction Outline of Contributions, Results Research Contributions 1 We present the first characterization study of deleted questions on Stack Overflow posted over 5 years 2 Longitudinal study of deleted questions, community voting patterns, deletion behavior by question owners and discover question quality structure 3 We build a predictive model for deleted question prediction Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

17 Table of Contents Deleted Questions on Stack Overflow 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

18 Deleted Questions on Stack Overflow What and Who? What and Who? What is a Deleted Question? Very low quality Dormant Activity Extremely Off Topic Who can Delete a question? Question Authors/Owners Elected community moderators Experienced Users(10,000+ reputation) can vote Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

19 Deleted Questions on Stack Overflow What and Who? What and Who? What is a Deleted Question? Very low quality Dormant Activity Extremely Off Topic Who can Delete a question? Question Authors/Owners Elected community moderators Experienced Users(10,000+ reputation) can vote Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

20 Deleted Questions on Stack Overflow Stack Overflow Deleted Questions Examples Stack Overflow Deleted Questions Examples Id Title Score Get drive information (free space, etc.) for -50 drives on Windows and populate a memo box plzz can u help me NDTV ipad app screen design I need to see this q fast..pleash PostgreSQL stupidity hi question about mathematics -3 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

21 Deleted Questions on Stack Overflow How and What Happens Next? How and What Happens Next? How are questions Deleted? Votes scales to the number of answers and the up votes on the answers Minimum of 3- votes and a maximum of 10-votes required Moderators, authors and experienced users ( reputation) points are able to view these questions What happens to a Deleted question? Remain deleted or Undeleted Undeleted similar vote procedure Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

22 Deleted Questions on Stack Overflow How and What Happens Next? How and What Happens Next? How are questions Deleted? Votes scales to the number of answers and the up votes on the answers Minimum of 3- votes and a maximum of 10-votes required Moderators, authors and experienced users ( reputation) points are able to view these questions What happens to a Deleted question? Remain deleted or Undeleted Undeleted similar vote procedure Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

23 Deleted Questions on Stack Overflow Stack Overflow Deleted Question Lifecycle Stack Overflow Deleted Question Lifecycle Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

24 Table of Contents Characterization Study of Deleted Questions 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

25 Characterization Study of Deleted Questions Stack Overflow Dataset Details Stack Overflow Dataset Details Database dumps between August 2008 to June Months January February March April May June July August September October November December Total 24 Database Snapshots Information Questions, Answers, Comments, Votes and Badges Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

26 Characterization Study of Deleted Questions Stack Overflow Dataset Details Stack Overflow Dataset Details Stack Overflow fro August 2008 June 2013 Users Questions Answers Votes Ratio of Answers to Questions 2.05M (936k askers, 630k answerers) 5.1M (60.22% with accepted answers) 9.4M (32.67% marked as accepted) 42.3M (70.5% +ve, 6.7% favorites) 1.84 Statistics of Deleted Questions Mean Median Min Max Distribution Questions per year 54,120 49,221 17, ,623 Answers Score x Views ,466 Favorites Comments Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

27 Characterization Study of Deleted Questions Stack Overflow Dataset Details Stack Overflow Dataset Details Stack Overflow fro August 2008 June 2013 Users Questions Answers Votes Ratio of Answers to Questions 2.05M (936k askers, 630k answerers) 5.1M (60.22% with accepted answers) 9.4M (32.67% marked as accepted) 42.3M (70.5% +ve, 6.7% favorites) 1.84 Statistics of Deleted Questions Mean Median Min Max Distribution Questions per year 54,120 49,221 17, ,623 Answers Score x Views ,466 Favorites Comments Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

28 Characterization Study of Deleted Questions Temporal Distribution Analysis Ratio of Deleted Questions Temporal Distribution Plot Ratio of Deleted Questions to Total Number of Questions Sep 09 Oct 09 Deleted Average = Nov 09 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Apr 11 May 11 Sep 11 Dec 11 Apr 12 Aug 12 Mar 13 Jun 13 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

29 Characterization Study of Deleted Questions Temporal Distribution Analysis Volume of Deleted Questions Temporal Distribution Plot Deleted Questions (Temporal) 270, Number of Deleted Questions Aug 09 Sep 09 Oct 09 Nov 09 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Apr 11 May 11 Sep 11 Dec 11 Apr 12 Aug 12 Mar 13 Jun 13 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

30 Characterization Study of Deleted Questions Temporal Distribution Analysis Temporal Distribution Analysis Key Findings 1 8% of questions are deleted 2 Deletion Question Audits in May lead to spikes 3 Increase in volume of deleted questions Ratio of Deleted Questions to Total Number of Questions Sep 09 Oct 09 Deleted Average = Nov 09 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Apr 11 May 11 Sep 11 Dec 11 Apr 12 Aug 12 Mar 13 Jun 13 Number of Deleted Questions Aug 09 Sep 09 Oct 09 Nov 09 Dec 09 Jan 10 Feb 10 Deleted Questions (Temporal) Mar 10 Apr 10 May 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Apr 11 May 11 Sep 11 Dec 11 Apr ,604 Aug 12 Mar 13 Jun 13 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

31 Characterization Study of Deleted Questions Community Takes Long Time to Detect... Community Takes Long Time to Detect Time taken to flag a Deleted Question Mean = Median = Number of Deleted Questions Percentage of Deleted Questions Time taken to mark 1st Delete Vote (days) Month+ 6-Months+ 1-Year+ 2-Years+ Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

32 Characterization Study of Deleted Questions...but Swift Action by Moderators...but Swift Action by Moderators Deleted vote distribution Votes Deleted Questions 1-vote 50,012 (79.45%) 2-votes 2,736 (4.35 %) 3-votes 9,009 (14.3%) 4-votes 463 (0.74%) 5+-votes 729 (1.16%) Total 62,949 Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

33 Characterization Study of Deleted Questions Authors Delete Questions to Salvage Reputation Question Deletion Initiator Other 0.04% 12.32% Moderator 87.64% Author Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

34 Characterization Study of Deleted Questions Authors Delete Questions to Salvage Reputation Authors Delete Questions to Salvage Reputation Time taken to delete questions Account Age - Question Owners 30.0 Age of Account (in days) Time (in days) Author Moderator Prior Posts Distribution Author Moderator Question Score Distribution Number of Posts 250 moderator author Score moderator author Percentile Score Denzil Correa, Ashish Sureka ( ACM WWW Percentile Score February 16, / 36

35 Characterization Study of Deleted Questions Question Quality Pyramidal Structure QZ=Percentage of Questions with Zero Score, QGZ=Percentage of Questions with Greater than Zero Score, PA=Percentage of Answers, PAA=Percentage of Accepted Answers, PAC=Percentage of Accepted Answers given that a question has an answer, CZ=Percentage of Comments with Zero Scores Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36 Community Value Percentage QZ QGZ Favorites View Count Percentage PA PAA PAC CZ Closed Deleted 0 Closed Deleted 0 Deleted Closed Code Snippet Percentage Characters in Question Body Deleted Closed Percentile Score

36 Characterization Study of Deleted Questions Question Quality Pyramidal Structure Word Cloud Tags on Deleted Questions Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

37 Characterization Study of Deleted Questions Question Quality Pyramid Question Quality Pyramidal Structure Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

38 Characterization Study of Deleted Questions Accidental Question Deletion Question Undeletion Distribution Plot Time (in seconds) Time taken to undelete Author (Median = 14s) Moderator (Median = 29s) Percentile Score Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

39 Table of Contents Deleted Question Prediction 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

40 Profile Based Features Deleted Question Prediction Features for Classification Features marked with are generated using LIWC2007. Set Type Features S A Profile Age of Account Previous Questions with -ve score Previous Questions with +ve score Previous Questions with 0 score Previous Answers with -ve score Previous Answers with +ve score Previous Answers with 0 score Number of Previous Questions Number of Previous Answers Number of Previous Badges Questions to Age of Account Ratio Answers to Age of Account Ratio Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

41 Deleted Question Prediction Community Based Features Features for Classification Features marked with are generated using LIWC2007. Set Type Features S B Community Average Answer Score Average Question View Counts Average Number of Comments Average Favorite Votes Average Question Score Average Number of Accepted Answers Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

42 Deleted Question Prediction Content Based Features Features for Classification Features marked with are generated using LIWC2007. Set Type Features S C Content Number of URLs Number of Previous Tags Code Snippet Length LIWC score of Personal Pronouns LIWC score of Pronouns LIWC score of Space words LIWC score of Relativity words LIWC score of Inclusive words LIWC score of Cognitive Process words LIWC score of Social words LIWC score of 1st person singular pronouns Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

43 Deleted Question Prediction Syntactic Based Features Features for Classification Features marked with are generated using LIWC2007. Set Type Features S D Syntactic LIWC score of Function Words LIWC score of Conjunctions LIWC score of Prepositions Number of characters in body Number of alphabetical characters in body Number of upper case characters in body Number of lower case characters in body Number of digit characters in body Number of white case characters in body Number of special characters in body Number of punctuation marks in body Number of words in body Number of short words in body Number of unique words in body Average body word length Number of characters in title Number of words in title Average title word length S A =12, S B =6, S C =11, S D =18, Total = 47 features Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

44 Deleted Question Prediction Experimental Testbed, Setup and Classifier Experimental Testbed, Setup and Classifier Challenges, Issues etc. High imbalance dataset 8% only in +ve class Reputation of the user at question creation time is not available Prediction at question creation time No particular winner discriminatory feature Dataset 470,096 questions Deleted (+ve class) 235,048 questions Non-Deleted (-ve class) 235,048 questions (10 times) Classifier Adaboost Learning Rate 1.0 Base Classifier Decision Tree Number of Estimators 100 Boosting Algorithm SAMME.R Cross Validation 10-fold Classification Runs 10-times (one for each +ve/-ve pair) Training-Testing split 70-30% Feature Sets {S A },{S A, S B }, {S A, S B, S C }, {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

45 Deleted Question Prediction Experimental Testbed, Setup and Classifier Experimental Testbed, Setup and Classifier Challenges, Issues etc. High imbalance dataset 8% only in +ve class Reputation of the user at question creation time is not available Prediction at question creation time No particular winner discriminatory feature Dataset 470,096 questions Deleted (+ve class) 235,048 questions Non-Deleted (-ve class) 235,048 questions (10 times) Classifier Adaboost Learning Rate 1.0 Base Classifier Decision Tree Number of Estimators 100 Boosting Algorithm SAMME.R Cross Validation 10-fold Classification Runs 10-times (one for each +ve/-ve pair) Training-Testing split 70-30% Feature Sets {S A },{S A, S B }, {S A, S B, S C }, {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

46 Deleted Question Prediction Experimental Testbed, Setup and Classifier Experimental Testbed, Setup and Classifier Challenges, Issues etc. High imbalance dataset 8% only in +ve class Reputation of the user at question creation time is not available Prediction at question creation time No particular winner discriminatory feature Dataset 470,096 questions Deleted (+ve class) 235,048 questions Non-Deleted (-ve class) 235,048 questions (10 times) Classifier Adaboost Learning Rate 1.0 Base Classifier Decision Tree Number of Estimators 100 Boosting Algorithm SAMME.R Cross Validation 10-fold Classification Runs 10-times (one for each +ve/-ve pair) Training-Testing split 70-30% Feature Sets {S A },{S A, S B }, {S A, S B, S C }, {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

47 Deleted Question Prediction Experimental Testbed, Setup and Classifier Experimental Testbed, Setup and Classifier Challenges, Issues etc. High imbalance dataset 8% only in +ve class Reputation of the user at question creation time is not available Prediction at question creation time No particular winner discriminatory feature Dataset 470,096 questions Deleted (+ve class) 235,048 questions Non-Deleted (-ve class) 235,048 questions (10 times) Classifier Adaboost Learning Rate 1.0 Base Classifier Decision Tree Number of Estimators 100 Boosting Algorithm SAMME.R Cross Validation 10-fold Classification Runs 10-times (one for each +ve/-ve pair) Training-Testing split 70-30% Feature Sets {S A },{S A, S B }, {S A, S B, S C }, {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

48 Deleted Question Prediction Experimental Testbed, Setup and Classifier Experimental Testbed, Setup and Classifier Challenges, Issues etc. High imbalance dataset 8% only in +ve class Reputation of the user at question creation time is not available Prediction at question creation time No particular winner discriminatory feature Dataset 470,096 questions Deleted (+ve class) 235,048 questions Non-Deleted (-ve class) 235,048 questions (10 times) Classifier Adaboost Learning Rate 1.0 Base Classifier Decision Tree Number of Estimators 100 Boosting Algorithm SAMME.R Cross Validation 10-fold Classification Runs 10-times (one for each +ve/-ve pair) Training-Testing split 70-30% Feature Sets {S A },{S A, S B }, {S A, S B, S C }, {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

49 Deleted Question Prediction Classification Performance Classification Results and Evaluation Confusion Matrix Confusion Matrix Prediction Performance True Predicted Deleted Non-Deleted Deleted 65.9% 34.1% Non-Deleted 33.9% 66.1% Accuracy, F1 and AUC score Classification performance on incremental feature sets based upon multiple evaluation metrics F1 score, Accuracy and Area-Under-Curve(AUC) Feature Set F1 Accuracy AUC {S A } {S A, S B } {S A, S B, S C } {S A, S B, S C, S D } Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

50 Deleted Question Prediction Classification Results and Evaluation Feature Importance Relative Importance Cognitive Process Words Average Body Length Relative Words Prev. Questions with 0 score Prev. Answers with +ve score Questions to Age of Account Ratio Pronouns Function Words Title Chars Space Words Whitespace Chars Prev. Questions Average Accepted Answers Personal Pronouns Prev Questions with +ve score Upper Case Chars Prepositions Conjunction Words Prev. Answers with -ve score Prev. Questions -ve Score Percentage Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

51 Table of Contents Conclusion 1 Introduction 2 Deleted Questions on Stack Overflow 3 Characterization Study of Deleted Questions 4 Deleted Question Prediction 5 Conclusion Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

52 Conclusion Conclusion Conclusion 1 We investigate the phenomena of deleted questions on Stack Overflow 2 We present our characterization study and draw multiple key insights based on temporal, community patterns and content analysis 3 We build a predictive model to classify deleted questions with 66% accuracy 4 We find that deleted question are extremely poor in nature 5 Our study benefits the Stack Overflow community both the users as well as the community elected moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

53 Conclusion Conclusion Conclusion 1 We investigate the phenomena of deleted questions on Stack Overflow 2 We present our characterization study and draw multiple key insights based on temporal, community patterns and content analysis 3 We build a predictive model to classify deleted questions with 66% accuracy 4 We find that deleted question are extremely poor in nature 5 Our study benefits the Stack Overflow community both the users as well as the community elected moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

54 Conclusion Conclusion Conclusion 1 We investigate the phenomena of deleted questions on Stack Overflow 2 We present our characterization study and draw multiple key insights based on temporal, community patterns and content analysis 3 We build a predictive model to classify deleted questions with 66% accuracy 4 We find that deleted question are extremely poor in nature 5 Our study benefits the Stack Overflow community both the users as well as the community elected moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

55 Conclusion Conclusion Conclusion 1 We investigate the phenomena of deleted questions on Stack Overflow 2 We present our characterization study and draw multiple key insights based on temporal, community patterns and content analysis 3 We build a predictive model to classify deleted questions with 66% accuracy 4 We find that deleted question are extremely poor in nature 5 Our study benefits the Stack Overflow community both the users as well as the community elected moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

56 Conclusion Conclusion Conclusion 1 We investigate the phenomena of deleted questions on Stack Overflow 2 We present our characterization study and draw multiple key insights based on temporal, community patterns and content analysis 3 We build a predictive model to classify deleted questions with 66% accuracy 4 We find that deleted question are extremely poor in nature 5 Our study benefits the Stack Overflow community both the users as well as the community elected moderators Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

57 Conclusion Conclusion Thank You! Connect with me Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36

58 Conclusion Conclusion Thank You! Connect with me One more thing... It s Stack Overflow, not Stackoverflow. Denzil Correa, Ashish Sureka ( ACM WWW-2014 February 16, / 36