Last year, a longtime engineer at Facebook Inc. gathered data that revealed a controversial finding: Code written by women was rejected much more frequently than code written by their male colleagues, according to people familiar with the matter and screenshots of internal discussions viewed by The Wall Street Journal.
For many female engineers at Facebook, the finding confirmed long-held suspicions that their coding faced more scrutiny than men's.
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The results touched off a debate within Facebook over alleged gender bias among some of its most-valued employees: the engineers who build the features used by nearly two billion people every month. Chief Executive Mark Zuckerberg was asked about the findings during a weekly town hall meeting.
The outcry prompted senior Facebook officials to conduct their own review of the engineer's study. In an internal post published a month later, Jay Parikh, Facebook's head of infrastructure, attributed any gap in rejection rates to an engineer's rank, not gender. Many employees interpreted this new analysis as a sign that female engineers weren't rising at the same rate as men who joined the company around the same time.
In a statement to the Journal, a Facebook spokeswoman described the initial analysis as "incomplete and inaccurate -- performed by a former Facebook engineer with an incomplete data set." The spokeswoman confirmed Mr. Parikh's analysis, which was based on confidential data unavailable to most employees. The spokeswoman added that there aren't enough women at senior engineering levels at Facebook and across the technology industry.
The Journal wasn't able to independently verify the results of either analysis or assess their methodology.
Like other major tech companies, including Google parent Alphabet Inc. and Apple Inc., Facebook has struggled to increase the share of women and underrepresented minorities in its ranks.
The absence of women is particularly felt in engineering, which from college classrooms to the workplace has been seen as a man's field. Women account for 17% of technical roles at Facebook, according to its latest diversity report.
Engineers write the code that is the bedrock of every feature launched by Facebook, from nearly imperceptible tweaks like the color of a button to new features like Facebook Stories. Each of these changes is subject to a code review by colleagues, a process similar to peer-review in academia. The code shapes the user's experience, and experts say the absence of diverse viewpoints on a coding team can lead to a product ignoring the needs of certain categories of users.
"Especially for mass consumer products, there are just going to be blind spots," said Tracy Chou, a diversity advocate and former software engineer at Pinterest Inc.
The initial analysis found that female engineers received 35% more rejections of their code than men, according to screenshots of the engineer's report posted last September. The engineer, who was described as having been at Facebook several years, said she conducted her analysis "so that we can have an insight into how the review process impacts people in various groups," according to screenshots of her internal post.
She said she analyzed five years of data to come to her finding about the higher rejection rate of code written by women. The engineer, whose identity couldn't be learned, pulled from Facebook's open repository of code-review data, which included details such as an engineer's tenure at the company as well as his or her team, city and gender.
Women also waited 3.9% longer to have their code accepted, and got 8.2% more comments and questions, according to the analysis.
Questioned about the engineer's report at a weekly Q&A with employees, Mr. Zuckerberg responded that gender bias was "an issue," said one person who observed the exchange.
The follow-up Facebook analysis, shared internally by Mr. Parikh in October, played down the gender gap, attributing the higher rejection rates to an engineer's level. Facebook used confidential human-resources data such as an engineer's rank; the first study used the length of time an engineer worked at Facebook.
Engineering roles at Facebook are broken into eight levels, starting at E3 and going up to E10.
When factoring in level, the difference in rejection rates based on gender "shows no statistically significant difference," wrote Mr. Parikh in the post.
Experts and former employees say both studies had flaws. The first may not have taken into account an engineer's previous experience before joining Facebook, while the official analysis failed to offer enough data to conclusively rule out gender bias.
Employees responded to Mr. Parikh's post by asking Facebook to share more detailed data, such as the percentage of female engineers at every level. The new analysis, they said, suggested that women were being held at levels where their code is rejected more often. "Thanks for this analysis but I find these results deeply disturbing," one employee wrote.
Facebook declined, saying it couldn't share private employee information.
In his post, Mr. Parikh acknowledged that the small discrepancy was "still observable and felt by many of you." He urged employees to take a voluntary training course to help employees identify and offset inherent prejudices.
"Consider the ways you could be a bias interrupter in your daily life," Mr. Parikh wrote.
Corrections & Amplifications
This article was corrected at 3:13 p.m. ET because the original version ave the incorrect percentage of women in technical roles at Facebook as 13%. Women account for 17% of technical roles there.
"Facebook's Female Engineers Claim Gender Bias," at 11:13 EDT Tuesday, gave the incorrect percentage of women in technical roles at Facebook. Women account for 17% of technical roles there.
(END) Dow Jones Newswires
May 02, 2017 15:28 ET (19:28 GMT)