Measure the improvement of Google search algorithm
On the day of Google's 15th birthday, Google released its new "Hummingbird" search algorithm, this is the first time that Google changes its search algorithm since 2010 after the Caffeine algorithm. It will affect 90% of search results, according to Amit Singhal,.
Some may be curious about how Google measures the improvement of a new search algorithm. There are many factors need to be considered, for example, accuracy, relevance, search depth etc. According to Amit Singhal,
Finally, Google's most experienced search engineers carefully review the data from all the different experiments and decide if the change is approved to launch or needs to be refined and retested.
For details about measurement of search engine algorithms, you can refer a more technical version :
It's a sarcastic picture describing how heavy the haze is in Beijing on Christmas day. Every winter people in Beijing will suffer the heavy haze.