Food Recommenders...1. Christoph Trattner ACM RecSys Summer School - 10. September 2019 Food...
Transcript of Food Recommenders...1. Christoph Trattner ACM RecSys Summer School - 10. September 2019 Food...
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. Christoph Trattner ACM RecSys Summer School - 10. September 2019
Food RecommendersA Data Science Perspective
Prof. Christoph TrattnerUniversity of Bergen
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Where do I come from?
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Research Focus
BigData
DataAnalytics
PredictiveModeling
Social Network DataOnline Communities Data
Web DataOpen Data
Understand how people behave
Theories
e.g. socialpsychology
RecSys
Behavioral Data Science
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Agenda
1. Motivation2. DS: Healthiness of Online Food3. RS: State-of-the-art & Health-aware Food RecSys4. DS: Linking Online to Offline5. DS: Predicting Item Popularity (Factor Analysis)6. DS/RS: Factors & Food RecSys7. RS: Altering Food Choice with RecSys8. RS: Recommending Similar Foods9. RS: Collaborative Filtering vs Content-Based10.The Future & Conclusions
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Part 1: Motivation
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Why is research into Food RecsysImportant?
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Why is that important?
§ Food is one the main concepts that shapes how good we feel and how healthy we are
§ According to the WHO, if common lifestyle risk factors, among others diet-related ones, were eliminated, around 80% of cases of heart disease, strokes and type 2 diabetes, and 40% of cancers, could be avoided (European Comission Recommendation C(2010) 2587 final, 2010).
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ProblemHealth is decreasing World Wide
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The approaches I am discussing today are all online food recommender
approaches!
Why Online?
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Most food interactions nowadays online
According to recent market research over 50%
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Amazon
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Part 2: Healthiness of Online Food
(Recipes)
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RQ: How healthy are online food items (recipes) actually?
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Nutrition Facts
Basic statistics:
§ 60,983 recipes§ 1,032,226 ratings§ 17,190,534 bookmarks
http://allrecipes.com
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According to Alexa.com
Allrecipes.com popularity
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How can we determine the healthiness of online recipes?
Trattner, C. Elsweiler, D. and Simon, H. Estimating the Healthiness of Internet Recipes: A Cross-Sectional Study. Frontiers in Public Health, 2017.
Trattner, C. and Elsweiler, D. Investigating the Healthiness of Internet-Sourced Recipes: Implications for Meal Planning and Recommender Systems. In Proceedings of the World Wide Web Conference (WWW), 2017.
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FSA food health criteria
Determining the healthiness of recipes
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WHO
food
hea
lth c
riter
ia
Who. Diet, nutrition and the prevention of chronic diseases. World Health Organ TechRep Ser, 916(i-viii), 2003.
Determining the healthiness of recipes
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Results
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Trattner, C. Elsweiler, D. and Simon, H. Estimating the Healthiness of Internet Recipes: A Cross-Sectional Study. Frontiers in Public Health, 2017.
Online food is unhealthy L
e.g. Tesco
Allrecipes
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FSA
crite
ria
Online food (recipes) is unhealthy L
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Online food is unhealthy L
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User perception
Results when asking users how healthy categories are on Allrecipes.com
(Kappa κ = .165, z = 42, p < .001)
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With which types of recipes do user interact the most?
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People seem to like unhealthy recipes
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Part 3: State-of-the-art & Health-aware Food
RecSys
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How healthy are recommendationsproduced by std. recommender systems
algorithms in terms of health?
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What is actually the current state-of-the-art in Food Recommenders?
Food Recommender Systems: Important Contributions, Challenges and Future Research Directions. Trattner, C. and Elsweiler, D. Collaborative Recommendations: Algorithms, Practical Challenges and Applications, World Scientific Publishing Co. Pte. Ltd., 2018
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*** p < .001
Results: Recommender Experiment
L
Libray: LibRecEval: 10 fold-cross validation
∆ = train − pred
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Can we improve std. recommendersystems in terms of health?
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Post-Filter scoring functions
Linear combinations as discussed in Elsweiler et al. (2015) did not work L
Re-ranking for health
D. Elsweiler, M. Harvey, B. Ludwig, and A. Said. Bringing the "healthy" into food recommenders. In Proc. of DRMS’15., pages 33–36.
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Results: Recommender (2)
Note: similar results with bookmarks
L
J
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Conclusions§ Only a small percentage of Allrecipes.com recipes can be
considered healthy according to WHO and FSA guidelines.
§ Users are to some extent able to judge how healthy categories will be, but often disagree.
§ Interaction data reveals that people are most positive about the unhealthy recipes.
§ Current state-of-the-art recommender algorithms in general produce unhealthy recommendations.
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Part 4: Linking Online & Offline
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Can we find a link between the online and offline world?
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Abbar, S., Mejova, Y., & Weber, I. (2015). You tweet what you eat: Studying food consumption through twitter. ACM CHI 2015.
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Correlation between food mentions on Twitter & Obese
p=.772s=.784
Abbar, S., Mejova, Y., & Weber, I. (2015). You tweet what you eat: Studying food consumption through twitter. ACM CHI 2015.
http://www.caloriecount.com/
§ 50 million tweets
§ Food related keywords
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…in RecSys, we typically use other types of signals…
Trattner, C., Parra, D. and Elsweiler, D. Monitoring obesity prevalence in the United States through bookmarking activities in online food portals. PLOS ONE 12(6), 2017.
Trattner, C. and Elsweiler, D. What online data say about eating habits. NATURE Sustainability, 2019.
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Research Questions
§ RQ1. To what extent do the nutritional properties of bookmarked recipes on Allrecipes.com correlate with obesity levels in the US?
§ RQ2. To what extent can temporal or geographical factors help in explaining obesity patterns?
§ RQ3. To what extent do nutrition factors explain the variance in obesity rates across the US?
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Dataset
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Dataset in detail
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Variables
Dependent Variable• Obesity prevalence (state / county level)
Independent Variables• Fat (of recipe)• Saturated Fat (of recipe)• Sugar (of recipe)• Sodium (of recipe)• Healthiness (of recipe)
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Results
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Trends over time
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Trends over time (zoom in)
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RQ1. To what extent do the nutritional properties of bookmarked recipes on Allrecipes.com correlate with obesity levels in the US?
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County Level Correlations
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State Level Correlations
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RQ2. To what extent can temporal or geographical factors help in explaining obesity patterns?
RQ3. To what extent do nutrition factors explain the variance in obesity rates across the US?
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Baseline Baseline+Time
Baseline+Time + FSA
Baseline+Time + Fat + Sugar
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Conclusion
§ We demonstrate significant and meaningful (i.e. sensibly interpretable) relationships between the nutritional properties of bookmarked recipes (sugar content, fat content and a combined FSA-score for recipes) and obesity incidence.
§ The good fit achieved by our models suggests that combining interaction data, geographical data and temporal data can be a useful in monitoring obesity incidence.
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Part 5: Predicting Item Popularity
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Why do people like the unhealthy recipes more?
Trattner, C., Moesslang, D. and Elsweiler, D. On the Predictability of the Popularity of Online Recipes. EPJ Data Science, 2018.
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...from the social psychology literature we know that there are several biases involved in when people cook or
select food, e.g.social & cultural factors, season, healthiness, visual
appeal
What makes a recipe actually to be chosen/popular?
Scheibehenne, B., Miesler, L., and Todd, P.M. (2007). Fast and frugal food choices: Uncovering individual decision heuristics. Appetite, 49, 578-589.
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Predicting Recipe Popularity=
Item Cold-Start Prediction
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Datasets
• Allrecipes.com• Kochbar.de
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Factors
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Temporality?
Clear temporalpatterns emerge
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Homophilie? Location?ingredientstype
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Visual Attractiveness?
San Pedro J, Siersdorfer S (2009) Ranking and classifying attractiveness of photos in folksonomies. In: Proceedings of the 18th international conference on world wide web. WWW ’09. ACM, New York, pp 771–780
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Other factors
• Recipe complexity• Instruction: Num. Words• Instruction: Num. Sentences• Entropy• LIX
• Recipe innovation
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Predicting popularity: Kochbar.de
Social Features
Random Forrest:90% accuracy
Social factors most important
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Predicting popularity: Allrecipes.com
Social Features
Random Forrest70% accuracy
Innovation & Image factors important
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How about other food cultures?
Zhang, Q., Trattner, C., Elsweiler, D. and Ludwig, B. Identifying Cross-Cultural Visual Food Tastes with Online Recipe Platforms. In Proceedings of the 11th International AAAI conference on Web and Social Media (ICWSM), 2019.
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China?
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Cross-Country Prediction
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Part 6: Factors & Food RecSys
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How would these features work in arecommendation scenario?
Trattner, C., Kusmierczyk, T. and Norvag, K. Investigating and Predicting Online Food Recipe Upload Behavior. Information Processing and Management. 2019.
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Predicting the top-3 food of recipe a userwould upload
Baselines
Social features win J
User-History Time
Categorial
Scoring functions:
Hig
her =
bet
ter
Loc
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Predicting Top-10 Ingredients
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Predicting Top-10 Ingredients
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Other Factors!
Gender & Food?
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Impact of gender
Prof. Dr. Eva Barlösius
Head of Leibniz Forschungszentrum Wissenschaft und Gesellschaft (LCSS)
Rocicki, M., Herder, E., Kusmierczyk, T. and Trattner, C. Plate and Prejudice: Gender Differences in Online Cooking. In Proceedings of the International Conference on User Modeling and Personalisation (UMAP), 2016.
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H1. Men Are Better Cooks
H2. Men Cook for Impressing
H3. Women Prefer to Cook Sweet Dishes, Men Prefer to Cook Meat Dishes
H4. Women Use Spices More Subtly
H5. Men Use More Gadgets for Cooking
H6. Men Are More Innovative
Hypotheses
Among recipes published by female cooks, 16.5% wereidentified as sweet dishes, significantly more than thefraction of 7.8% for male cooks
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To what extent can we identify the genderof the recipe authors?
Feature ImportanceClassification Results
RF=Random Forrest, LR=Logistic Regression, AB=Ada Boost
Most important
Hig
her =
bet
ter
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Gender-aware recommendations (predicting the recipes a user will like)
Most Popular Most Popularwith gender
Hig
her =
bet
ter
Collaborative Filtering
Collaborative Filtering with gender
Gender aware methods alwaysbetterJ
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Part 7: Altering Food Choice
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Can we alter food choices with recommenders?
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Study
Elsweiler, D.*, Trattner, C.* and Harvey, M. (* equal contribution). Exploiting Food Choice Biases for Healthier Recipe Recommendation. In Proceedings of the ACM SIGIR Conference (SIGIR), 2017.
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Which one of the two would you choose?
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User feedback
Title
Ingredients
Image
Nutrition
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User Study
Q: Which one of the two would you choose?
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User Study 1
User Study 2
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Nudging People Towards Healthy Food Choices
Developed an algorithm that can nudge people towards healthy food choices through images J
Less fat
More fatExploiting Food Choice Biases for Healthier Recipe Recommendation. Elsweiler, D.*, Trattner, C.* and Harvey, M. (* equal contribution). In Proceedings of the ACM SIGIR Conference (SIGIR), 2017.
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Part 8: Recommending Similar Food
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How can I build a simple similar Item recommender for food?
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ProblemIngredients
DirectionsImage
Title
Similar Item Recommendations
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Problem
Reference Item
Item 1 Item 2 Item 3 Item 4 Item 5
Most Similar Least Similar
Sim(a,b)=100%Sim(a,b)=90% Sim(a,b)=70% Sim(a,b)=50% Sim(a,b)=45%
Rco
mm
ende
dIte
ms
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Paper
Trattner, C. and Jannach, D. Learning to Recommend Similar Items from Human Judgements. User Modeling and User-Adapted Interaction Journal. 2019.
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Research Questions
• RQ1. Which types of features and which specific features determine the similarity between items as perceived by users?
• RQ2. Which specific combination of features is suited to predicting user-perceived similarity levels?
• RQ3. Do models with higher prediction accuracy lead to a higher perceived item similarity?
• RQ4. How do users assess the usefulness of recommendations that are based on different similarity functions?
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What makes recipes similar?
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sim(a,b)
sim(a,b)
sim(a,b)
sim(a,b)
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Features for Similar RecipeRecommendations
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Example Image Features
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DNN Images Features: VGG 16
Take these layers for classification (fc1 or fc2)
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VGG16 Implementation
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How did we collect the ground truth?
A: Amazon’s Mechanical Turk
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Amazon Mechanical Turk
URL: https://www.mturk.com/• Crowdsourcing platform for micro task• Founded March 2007- 100,000 workers in over 100
countries.• 2011 - over 500,000 workers from over 190 countries
in January 2011.• Tasks = Hits• Workers = Turkers
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What do I have to do
...as a turker?
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Mtruk.com - Worker
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What do I have to do
...as a hit requester?
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Mtruk.com - Requester
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User Study Design: Ground truth study
Mturk StudyPage
PostQuestionnaire
Study Code
10 random Recipe pairs
…
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Rec
ipe
Stud
y
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Results
Recipe Study: 400 turker
with 98% hit accept rate and min. 500 hits in the past
In total: 4,000 user estimates
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Recipe Results: User Characteristics
~45% of all users passed theattention check
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RQ1. Which types of features and which specific features determine the similarity between items as perceived by users?
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Recipe Results: Feature Correlations
Higher is better1 = 100%
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Recipe Results: Cue Usage
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RQ2. Which specific combination of features is suited to predicting user-perceived similarity levels?
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Recipe Results: Machine Learning performance when features are combined
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User Study Design: Validation Study
Mturk StudyPage
PostQuestionnaire
Study Code
5 random recipes with 5 recommended lists
.
.
.Algorithm: X
Algorithm: Title
Algorithm: Image
RandomAlgorithm
Assignment
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Rec
ipe
Stud
y
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Results
Recipe Study: 800 users
with 98% hit accept rate and min. 500 hits in the past
In total: 24,000 user estimates
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RQ3. Do models with higher prediction accuracy lead to a higher perceived item similarity?
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Recipe Results: Perceived Sim & Interest in Trying Recommendations
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RQ4. How do users assess the usefulness of recommendations that are based on different similarity functions?
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Recipe Results: Helpfulness, Diversity, Surprise, Excitingness
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Conclusions
• Our work demonstrates the feasibility of learning similarity functions from human judgements.
• It also turned out that considering these human judgements is a necessity, because experts can err and because self assessments by users regarding the relative importance of certain factors might be misleading.
• Our experiments and studies also showed that it is important to consider several aspects in parallel.
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What are we currently working on?
(User Characteristics)
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User Characteristics
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Part 9: Collaborative Filtering vs Content-based
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And what about CB vs CF in the Food Domain?
Trattner, C. and Elsweiler, D. An Evaluation of Recommendation Algorithms for Online Recipe Portals. In Proceedings of the HealthRecSys workshop co-located with ACM RecSys, 2019.
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CF vs CB in Recipe RecSys
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Part 10: The Future & Conclusions
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What is the Future?
Sustainable Food Recommender Systems
What online data say about eating habits. Trattner, C. and Elsweiler, D. NATURE Sustainability, 2019
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Conclusions
• In order to get started with Food RecSys:
• If you need data or code - email me J• Rest can be found on my website:
http://christophtrattner.com
Food Recommender Systems: Important Contributions, Challenges and Future Research Directions. Trattner, C. and Elsweiler, D. Collaborative Recommendations: Algorithms, Practical Challenges and Applications, World Scientific Publishing Co. Pte. Ltd., 2018.
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Thank you!
Prof. Christoph Trattner
Email: [email protected]: christophtrattner.com
Twitter: @ctrattner
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Some Referencesq Food Recommender Systems: Important Contributions, Challenges and Future
Research Directions. Trattner, C. and Elsweiler, D. Collaborative Recommendations: Algorithms, Practical Challenges and Applications, World Scientific Publishing Co. Pte. Ltd., 2018
q Monitoring obesity prevalence in the United States through bookmarking activities in online food portals. Trattner, C., Parra, D. and Elsweiler, D. PLOS ONE 12(6), 2017.
q Exploiting Food Choice Biases for Healthier Recipe Recommendation. Elsweiler, D.*, Trattner, C.* and Harvey, M. (* equal contribution). In Proceedings of the ACM SIGIR Conference (SIGIR), 2017.
q Investigating the Healthiness of Internet-Sourced Recipes: Implications for Meal Planning and Recommender Systems. Trattner, C. and Elsweiler, D. In Proceedings of the World Wide Web Conference (WWW), 2017.
q Estimating the Healthiness of Internet Recipes: A Cross-Sectional Study. Trattner, C. Elsweiler, D. and Simon, H. Frontiers in Public Health, 2017.
q Plate and Prejudice: Gender Differences in Online Cooking. Rocicki, M., Herder, E., Kusmierczyk, T. and Trattner, C. In Proceedings of the International Conference on User Modeling and Personalisation (UMAP), 2016.
q Understanding and Predicting Online Food Production Patterns. Kusmierczyk, T., Trattner, C. and Norvag, K. In Proceedings of the ACM Conference on Hypertext and Social Media (Hypertext), 2016.