Social Computing Flashcards
Confusion Matrices
a more accurate substitute for the basic probability that a user gives the correct answer
Consequences of information asymmetry
Leads to buyers making an adverse selection as the market consists of poor-quality items, as explained in The Lemon Problem
Moral Hazard
Hazards that arise when an individual is incentivised to take greater risks as they are shielded from the negative consequences of their actions.
Such as, failing to uphold an agreement after payment as there is no consequences to their actions
Purpose of Reputation Systems
Mitigate moral hazards and address the information asymmetry that leads to adverse selections in the market by quantifying the trust of individuals/entities using the wisdom of the crowd
Calculate Reputation Value
Calculated through averages of user ratings, improved with:
- correction for user bias
- weighted rankings (based on user trustworthiness i.e. past ratings rated helpful by others)
Confidence Values
Convey the certainty of the accuracy of a reputation values
Challenges with Reputation Systems
Ballot Stuffing
Slander & Self Promotion
Whitewashing
Fear of Retaliation
Individual Bias
Quality Variations
Lack of Incentives
Ballot Stuffing
Multiple ratings from a single user
To tackle, ensure there is some effort-based (or monetary) cost to providing rating
Slander & Self-promotion
Competitors place reviews to damage sales of others
To tackle, require identity authentication and proof of transaction. Allow ratings of helpfulness of ratings. Use trust interference based on a user’s history
Whitewashing
Users change their identity to reset their reputation
To tackle, ensure there is an effort-based cost to changing identity e.g. linking phone number
Fear of Retaliation
Users fear retaliation and give overly positive ratings
To tackle, simultaneously disclose buyer and seller ratings e.g. Airbnb. Or prevent seller from rating buyers
Individual Bias
Users rate overly positive or negative
To tackle, adjust score based on history
Quality Variations
Sellers sell low-value items to achieve a good reputation value, only to exploit this and sell low quality goods at high value
To tackle, weight ratings based on price and recency
Lack of Incentives
Users may not want to provide ratings
To tackle, provide non-monetary, or monetary, rewards
Motivations to Participate in Crowdsourcing
Financial Rewards
Self-development
Enjoyment
Altruism (Selflessness)
Social Aspects (Recognition, Competition, Validation)
Social Mobilisation
Address complex search problems through referral schemes e.g. recursive incentive scheme
Output-agreement Mechanism
Gamification technique
ESP Game for Image Labelling
Input-agreement Mechanism
Gamification technique
TagATune Game
Provide descriptions and guess if listening to same song as peer
Benefit of Gamification
Increased engagement
Anchoring Effect
Individuals rely heavily on the first piece of information they receive (initial pay) when making subsequent judgments or estimations
Expert Crowdsourcing Attributes
Quality is highly important
less workers relied on
Crowdsourcing Contests
Individuals submit solutions and best submission is rewarded
- Workers behave strategically and pick tasks with less competition
- Early success experience is critical for workers to continue contributing
- Only a small amount of workers succeed
Multi-armed Bandit Problem
Describes the challenge of maximising rewards when balancing the exploration of new options and the exploitation of the best option known
ε-greedy
ε-greedy considers a probability of whether to explore or exploit.
ε-greedy(0.05) is 5% chance of EXPLORATION and 95% chance of EXPLOITATION
