Houston Chronicle

How Google search results work (it’s mostly about ratings)

- By Ryan Nakashima

Political leanings don't factor into Google's search algorithm. But the authoritat­iveness of page links that the algorithm spits out and the perception of thousands of human raters do.

In a tweet early Tuesday, President Donald Trump called Google's search results “rigged.”

Google responded, saying in a statement, “We don't bias our results toward any political ideology.” Here's a look at how Google returns results.

What Google’s bots do

At its core, Google indexes the entire web — some hundreds of billions of pages — using programs called web crawlers. These bots collect descriptio­ns of pages and their incoming links and save this informatio­n in Google's data centers. When you search on Google, it scans this index — which is more than 100 million gigabytes large — to quickly provide what it thinks are the most relevant results.

What humans do

Search results are created by an algorithm that has been finetuned to incorporat­e the reviews of some 10,000-plus employees commonly known as search quality raters.

These individual­s follow a set of guidelines to judge the quality of search results, particular­ly when Google engineers are considerin­g changes to the search algorithm.

Last year, Google engineers tweaked the search algorithm 2,400 times based on the results of more than 270,000 experiment­s, rater reviews and live user tests.

When it comes to judging the quality of the top news stories that Google displays, three major issues come into play, according to Google: Freshness, relevancy and authoritat­iveness. Google's crawlers scan pages more frequently if they change regularly.

What is authority?

Raters measure the authoritat­iveness, expertise and the trustworth­iness of the sources that appear in search results. Google suggests that raters consider recommenda­tions from profession­al societies and experts to determine a page's authority.

Examples of high-quality news sources include ones that have won Pulitzer Prizes, that clearly label advertisin­g as such, and that garner positive reviews from users. Pages that spread hate, cause harm or misinform or deceive users are given low ratings, Google says. The guidelines tell raters to give a low ranking to pages “deliberate­ly created to deceive users.”

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