Milad Shokouhi Microsoft Research Cambridge · Query Trends in Bing Logs Search Solutions 2012...
Transcript of Milad Shokouhi Microsoft Research Cambridge · Query Trends in Bing Logs Search Solutions 2012...
Spike & Go (e.g. Whitney Houston Funeral)
• How to detect the spiking intent quickly?
• How to rank news documents?
Spike and remain (e.g. Kindle Fire)
• How to detect the official page quickly?
• How to index and rank such pages correctly?
Seasonal Queries (e.g. Halloween)
• How to classify seasonal queries?
• How to switch between years?
Auto-Completion Trie
Candidate Scores
Prefix Tree
Keys on edges
Nodes store past queries
Scores are Past Frequencies
Time-Sensitive Auto-Completion Ranking
MPC Time-Sensitive
MPC 𝑃 = 𝑎𝑟𝑔𝑚𝑎𝑥𝑞∈𝐶(𝑝) 𝑤(𝑞)
w 𝑞 = 𝑓(𝑞)
𝑓(𝑖)𝑖∈𝑄
TS 𝑃, 𝑡 = 𝑎𝑟𝑔𝑚𝑎𝑥𝑞∈𝐶(𝑝) 𝑤(𝑞|𝑡)
w 𝑞|𝑡 = 𝑓 𝑡 (𝑞)
𝑓 𝑡(𝑖)𝑖∈𝑄
P: Prefix; q: Suggestion; t: Time
Time-Series Forecasting
A time-series is a set of discrete or continuous
observations over time.
Applications
Data modeling
Forecast
Examples
Sales figures
Student enrolment
CO2 rate
Query popularity
Single Exponential Smoothing
The data points are modeled with a weighted average.
𝑦, 𝑦 , 𝑦 : Respectively represent actual, smoothed and predicted values at time t.
λ: Smoothing constant
Forecast:
Double Exponential Smoothing
𝑦, 𝑦 , 𝑦 : Respectively represent actual, smoothed and predicted values at time t
𝜆1, 𝜆2: Smoothing constants
𝐹𝑡: Trend factor at time t
Forecast:
Triple Exponential Smoothing
𝑦, 𝑦 , 𝑦 : Respectively represent actual, smoothed and predicted values at time t
𝜆1, 𝜆2, 𝜆3: Smoothing constants
𝐹𝑡: Trend factor at time t
𝑆𝑡: Seasonality factor at time t
τ: Length of seasonal cycle
Forecast:
when to plant tulips vs. when to plant tomatoes
In our SIGIR’12 paper we showed that
Short history is better for prediction
Prediction error and autocompletion
ranking quality are correlated
Conclusions
Freshness matters in search, a lot
There are different type of time-sensitive queries
With enough data, temporal trends can be modeled
accurately