Glass half empty? How accurate is Glassdoor Data?

Glassdoor versus Murmur ratings: Percentage of employees who would recommend 13 New Tech companies as a place to work.

Glassdoor is an online forum where people are invited to rate their current or former companies. Glassdoor provides a valuable service because it allows people to anonymously provide feedback to other job seekers, as well as the company itself.

However, as other research has shown, in many cases there is almost no relationship between Glassdoor ratings and more comprehensive internal surveys. Glassdoor has great uptake in the New Tech space (see below). As we have comprehensive New Tech data, we thought it might be interesting to draw our own comparison.

We recently published a report based on our work with many of the world’s fastest growing New Tech companies. For many of those companies we have data on how likely employees say they are to recommend the company as a great place to work – similar to the Glassdoor measure asking if employees would recommend their company to friends or family.

This “recommendation question” is often used as a basis for deriving what is often called a Employee Net Promoter Score (eNPS) . We decided to take a look at some of the companies where we have good comparable data to the Glassdoor data.

We identified 13 New Tech companies. For these companies we had strong, recent data (> 80% of employees) for the recommendation question. Plus these companies also had at least 5 Glassdoor reviews. The chart above shows the difference between our and the Glassdoor measures.

Quite clearly the Glassdoor scores are generally lower and in some cases more than 20% out relative to the more representative data from Murmur.

Glassdoor reviews tend to paint a more negative view of companys’ recommendation scores. Given the variability it is unlikely that anyone could rank companies using Glassdoor. We did notice a slight trend towards better comparisons when there were more reviews. However, the effect was not terribly strong.

These results match the larger sample comparisons provided by other research mentioned above. These suggest that Glassdoor reviews may only provide a very selective and narrow view of what companies are truly like to work for. It might be useful for Glassdoor to publish internal data where it can also be verified and deemed comparable as this would enable prospective employees to make a more informed decision.


  • Valerian Precop

    I had a look at Glassdoor (and some other websites like it).

    The idea is good but very very very bad implemented and released to public.

    The pure fact that “employees” are allowed to anonymously add reviews (good or bad) just with a simple online registration is a nonsense.
    There is no way for a company to prevent bad reviews from “annoyed” (lightly said) former employees… no way the submission is properly validate.

    Did anyone from these websites thought what happens if the competitor of a company is suddenly deciding it would be good if they submit some “anonymous” reviews until they reduce their rival company reviews to crap – what is the impact on the HR/PR for the real company… on their efforts to hire new and specialized staff to bring the business to it’s real potential? Do you think a simple written text warning would scare those types of scamers?

    How can it be fair when grumpy / annoyed / fake people can add multiple bad (or good) reviews just by the simple fact that they have x number of email/gmail/facebook accounts?
    Anyone can use their x accounts to submit good reviews (for pumping up a company overview) or bad reviews (to diminish a company or someone in particular).

    It is a fact of live (and business): there are bad companies… but as well… there are bad employees…
    Very few people would ever add a fair review on these type of websites – it is a proven fact that is easier to get a letter of complaint from someone than a letter of thank you.

    I consider these type of websites that allow grumpy people to hide behind anonymity when talking bad of a company or someone in particular nothing more than pure scams. They build their business model on the back of angry people and hit many times exactly in the opposite direction of what they actually promote: fair reviews from employees to their companies (former companies).

    These are like having a big “always unlike button” on a company profile page.

    I would urge anyone that reads reviews on these type of websites to think, not twice, but ten times before trusting them. You are better off doing an interview at the respective company and as it is normally said… your instinct is the best guide in your life – trust your instinct and your intellect.

    PS: very good comment on how to take on these type of company reviews here (