March 11, 2013

How good is Glassdoor?

The growing popularity of job review sites like Glassdoor and CareerBliss is causing problems for many companies. We appreciate that these sites are trying to bring more transparency into what it’s like to work at a company—but unfortunately these sites are often not an accurate reflection of the workplace.

To test the accuracy of these sites, we compared WorkplaceDynamics’ data on 406 large companies surveyed in the last year, with those same companies’ corresponding reviews on Glassdoor. We found that there was virtually no correlation—the overall Glassdoor star rating was a very poor indicator of what it is really like to work at a company.

There are two main issues that we identified:

  1. Glassdoor typically has reviews from only a small percentage of employees at the company. At the 406 companies in the sample, there were 8,123 Glassdoor reviews, an average of 1.6% of the employees. As a comparison, we surveyed 315,212 employees at these companies, an average of 61.5% of the employees.
  2. Glassdoor reviews are posted by a disproportionate number of “grumpy” employees. We conservatively estimate that a company’s negative employees are 5 to 8 times more likely to post a review on Glassdoor than their positive employees.

These two factors can make the overall Glassdoor scores inaccurate. Good examples of this are Quicken Loans and The Container Store, which we recently named as #1 and #2 on our National Top Workplaces list.

Quicken Loans has a score of 3.2 stars on Glassdoor, and 46% of employees do not recommend this company to a friend (based on 140 reviews).

However, we found in our survey, based on 935 survey responses from employees at Quicken Loans, that only 2% of employees would not recommend the company (with a further 5% neutral). On average, employees rated working at Quicken loans a 90.3 on a scale of 0-99.

The Container Store has a similar score of 3.1 stars on Glassdoor and 46% of employees do not recommend this company to a friend (based on 218 reviews):

We found, based on 1,516 survey responses from employees at The Container Store, that only 3% of employees would not recommend the company (with a further 4% neutral). On average, employees rated working at The Container Store a 90.1 on a scale of 0-99.

So, while the intent of sites like Glassdoor is good, job seekers should think twice before making any decisions based on reviews from these sites when looking for a new employer.


How we did the analysis

As a dataset, we took the WorkplaceDynamics survey responses to the questions ‘I would highly recommend working at this company to others’ and ‘Out of 99 (where 99 is best and 0 is worst), I would rate working at this company as…’ for all the large companies that participated in the Top Workplaces program in Boston, Chicago, Dallas, Des Moines, Detroit and Minneapolis, and looked up the corresponding reviews (filtered by location) on Glassdoor for the questions ‘Your overall rating of this company’ and ‘Recommend this employer to a friend?’ There were 406 companies that had corresponding Glassdoor data.

Based on WorkplaceDynamics data (the total employee response rate and percentage of negative and positive responders) , we estimated the total number of grumpy and positive people working in those companies in those regions, and then looked to see the percentage of each category that had left a review on Glassdoor. This gave us the conservative estimate that grumpy employees are 5 to 8 times more likely to leave a review on job review sites than happy employees.

  • Lora Silver

    Did you pay attention to the employment status of the Glassdoor reviewers – current versus former employees? I always found it interesting (and appreciated) that Glassdoor included this field when leaving a review, although it is not a required field. WorkplaceDynamics surveys are by nature administered to current employees, while Glassdoor reviews are written by current or former employees — and I wonder how this difference might affect your analysis. I’d bet more of the Glassdoor reviewers are past employees rather than current employees, but I have no evidence for that! Thanks for sharing your method transparently, this was a really interesting read.

  • Al Taylor

    Hi Lora, we looked at all reviews, rather than splitting by current and former employees. I would love to see what the result of doing this is – but I can’t see a way to filter the scores by that demographic on Glassdoor. Nonetheless, it is interesting to think about what it would mean if the scores of former employees were lower than current employees – my sense is that it would either be driven by an even greater skew of disgruntled ex-employees being more likely to leave a negative review than happy ex-employees (the revenge of someone who has been fired!) or actually the company being good at letting go of employees that are not a good fit with the culture. From our data we see that being inspired by what an organization is trying to achieve, and how it does it, is critical to enjoying work, so a company being able to let go of people that don’t want to be on that journey is a good thing. I’m glad you found the research interesting – we certainly think it is fascinating.

  • Gerald A. Edgar

    Well reasoned article – tks for sharing! Accurate surveying is an art, a challenging one at best.

  • trying to keep it real

    Your article does not take into the way the larger companies document the employee satisfaction. I have worked for one of the top companies in the country to work for last 20 years and the employee satisfaction survey was only presented to those the company knew would give high recommendations. Supervisors were/are given the directive to provide these names to ensure only the right people give responses.

    Another thing your article does not take into account is that glass door and other sites like that are usually from people who have been at the company a long time. A lot of companies are very good at immediate motivation and seemingly like they are great companies to work for but truth be told large companies don’t motivate in the long run because they run to much like high school. Your happiness at those companies is only as long as you stay friends with the cool click.

    No dataset will truly give a potential employee a true idea of what it is like to work for that company. Everyone is different and not every place could make everyone happy. The potential employee will just have to try it and see.

  • Anon

    So when you have the results of a dynamics survey, administered at the wishes of the employer, you then give that to a prospective employee, is it valued objectively? The reality is which will they trust, an anonymous review site? Or one administered By the company…. Do a survey to find out….

  • Anita

    My problem with the site is that if you work for a business with multiple locations and owners, it’s not a very accurate measure because every place is different. There were some horror stories told about the company I work for, but they’re not reflective of my own location at all, so they also make companies look bad. Also, some of the reviews make me wonder if the problem wasn’t actually the reviewer…

  • ABC

    I was tracking a small company with employee strength of around 500 employees. I saw their score go up from 2.5 to 3 in 3 months. Number of reviews going up from 30 to 60 in same period of time.
    They earlier had scathing 1 star reviews. In the 3 month period I am referring to, almost all reviews were 5 stars with 4 stars in between.
    I see this practice of bumping up the scores with small companies.

    I would suggest to see dates of reviews and language used. If you see number of 5 starred reviews within small span of time for small companies with similar language, you can be pretty sure that someone inside HR is deliberately bumping up the scores by putting random positive reviews.

  • Gary Zenker

    You bring an important message to light: that information on sites such as Glass Door are biased toward the negative. People who are satisfied generally don’t have the same incentive to participate or be heard as those with an axe to grind. Yes, we can all acknowledge that companies may have other biases built into their own information collection. The results from any survey depends on the design of the survey which generally is driven by what you are trying to achieve with your data: truly uncover weaknesses and fix them, create a PR piece that portrays you as great, or instigate a lot of activity through the lowest hanging fruit: dissatisfied people who want to complain.

    You did a great job in pointing out that those viewing the data must understand that a survey system like Glass Door does not eliminate the biases that are inherent in their approach of surveying. I like the fact that you showed us actual comparison data to show where the data differs. So clearly, basing one’s opinion of a company based on a small sampling of griping people may well lead you to the wrong conclusion.

    This should remind us all that if we don’t take an interest in the facts behind the survey and collection of the data, we are as likely to draw the wrong conclusion as the right one (well, statistically, maybe more likely to draw the wrong conclusion).

    Thanks for the interesting post.

  • Jason Clark

    i would have to say glassdoor is very inacurrate, if you want a job review about bad companies you cant trust glassdoor, they remove negative job reviews, period. unfortunatly many, many companies are run by employers that employees hate, mainly because of their arrogance and slave labor tactics, which by the way exist in ALL companies. if the employer was a good one, why would the employee leave, some are which is why6 u see good reviews, however this doesnt take into account how many employers pad their own reviews, all my reviews have been deleted, the last one was a bad review on the company, because i was wrongfully terminated, w/o notice, i wouldnt give this company a bad review but then i got my last check which was very small, i questioned the payroll company, and they submitted my timecards which were altered by the employer removing hours, because he felt i wasnt productive enough, yet i am unable to say this on glassdoor, i never even cussed i just told it like it is, 25 ppl have wuit in a year it was so bad, but glassdoor just bans the reviews.

  • Pingback: Should Employers Fear Glassdoor Reviews?

  • Charles Tenant

    I question internal reviews all the time. In some industries people want their employer to get high marks because then they look like they are the shining star in the industry and that in itself looks great on your employees resumes. Even if the place is a torture chamber, employees will give it great marks because it looks best on paper! I question those who challenge the accuracy of Glassdoor (and I don’t work for them), some places really are bad to work at, and if your happy staff is so dedicated, they would all be posting great reviews. And of course it’s many former employees, when you end a relationship or transaction is when you make a comment.

  • just a passerby

    I built a database application exactly for this reason – but for interns to review their internship experiences. You can find it here:!/1

  • Jessica

    Great post!

    Another issue I’ve identified with Glassdoor specifically is a lack of accurate information about job title or status. Because the reviewer is able to enter their own info, my company has reviews with job titles that don’t even exist and reviews from former employees (who are very easy to identify) that incorrectly stated their job title or overstated their role. Glassdoor is vocal about the fact that because they can’t verify the info, they just go with whatever the reviewer says. There is little recourse for the company being reviewed. While we would not look to silence an opinion and recognize the site is not aimed at giving the company yet another platform to advocate their position, when the factual information is misstated, it causes confusion and provides limited value.

    One of the benefits of the survey you did is you’re able to control the fact-based demographic info, like job title, to give a more accurate picture of the opinions. It also ensures the disgruntled vocal minority isn’t drowning out the majority.


    Glassdoor is total fabricated information, they reject anyone posting legit facts on the site.

  • EasyReader

    Whether you’re happy or miserable at work depends a lot on your boss. If he or she has your back and supports your efforts while giving you the tools and information you need, life at work is great. You can work for The Greatest Company on The Planet, but without a good boss, you won’t be happy.