Overcoming Bias in Performance Reviews

Sep 8, 2023 | Appraisals and Performance Reviews

employee appraisal bias image of one employee being elevated

As an HR manager, you play a critical role in ensuring that your company’s performance review process is fair and unbiased. But let’s face it, bias has a way of sneaking into even the most well-intentioned evaluations. It’s a pervasive issue that can have far-reaching consequences, impacting both individual employees and the overall culture of your organisation.

In this blog post, we’ll delve into the topic of bias in performance reviews. Exploring the different forms it can take and the steps you can take to mitigate its effects. Hopefully, the tips we give here will help you improve your performance management process.

Performance appraisals are meant to be an objective assessment of an employee’s job performance. Providing valuable feedback for their growth and development. However, research has consistently shown that bias can taint these evaluations, leading to unfair outcomes.

As an HR manager, it’s crucial for you to be aware of these biases and take proactive measures to counteract them. Ensuring that your performance reviews are as fair and accurate as possible.

In the following sections, we’ll explore some common biases that can arise in performance reviews. We will also provide some practical strategies to address them head-on. So, let’s dive in and uncover the truth behind bias in performance reviews!

An Overview of Performance Review Bias Types

This is a list of the types of bias you might find affecting performance appraisals. It roughly ordering in prevalence order, ie, the most common type of bias at the top.

Confirmation bias
Halo effect bias
Recency bias
Primacy bias
Affinity bias
Similar-to-me bias
Gender bias
Horns effect bias
Leniency bias
Central tendency bias
Distance bias
Spill-over bias
Self-rater bias
Expediency bias
Idiosyncratic rater bias
Law of small numbers bias
We favour information that confirms our existing beliefs, neglecting opposing data.
A single positive trait influences our perception of someone's other unrelated characteristics.
We give more weight to recent events or information over older ones.
First impressions or early information have a lasting impact on our perception.
We tend to prefer individuals or ideas we like or feel an affinity for.
We are biased towards individuals or ideas that resemble our own characteristics or beliefs.
Favouring one gender over the other, often stemming from stereotypes or cultural norms.
Overgeneralised beliefs about a particular group, leading to biased judgment.
A single negative trait influences our perception of someone's other unrelated characteristics.
The tendency to evaluate people or situations more favourably than is warranted.
The tendency to avoid extreme judgments and rate people or situations as average.
Things closer to us (in time, space, or relationship) seem more important than they are.
Past evaluations or feelings influence our current assessment of an individual or situation.
Individuals may evaluate themselves differently compared to an external observer.
Making decisions based on what's easiest or readily available rather than what's accurate.
Individual biases based on personal values or beliefs that aren’t shared by others.
Drawing conclusions from a small amount of data, or seeing patterns where none exist.

Performance Review Bias Types in Detail

In this section, we will give more detail about each of the more common types of performance review bias. We also give examples of each bias type, and strategies for overcoming bias in performance reviews.

Confirmation bias

What is Confirmation bias?

Confirmation bias is the tendency to search for, interpret, and remember information in a way that confirms one’s preconceptions.

Example of Confirmation bias:

A manager has always viewed an employee as not very dedicated because they occasionally come in a few minutes late. As a result, the manager might overlook instances where the employee stays late, completes tasks ahead of schedule, or contributes beyond their role.

How to prevent Confirmation bias:

Actively seek out evidence that contradicts your beliefs. During performance reviews, focus on objective metrics and evidence rather than relying solely on memory or general impressions. Periodic self-checks for biases and using standardised evaluation metrics can also help.

Halo effect bias

What is Halo effect bias?

The Halo effect is when our opinion of someone in one area affects our opinion of them overall.

Example of Halo effect bias:

An employee recently made a significant sale or achieved a notable accomplishment. During the performance review, this single achievement might overshadow other areas where the employee might have underperformed or made errors.

How to prevent Halo effect bias:

Evaluate each performance area independently and avoid generalising one accomplishment or mistake to the entire review. Using structured feedback forms can help in maintaining focus on all relevant areas.

Recency bias

What is Recency bias?

Recency bias is the tendency to weigh recent events more heavily than earlier events.

Example of Recency bias:

If an employee made a mistake or had a significant achievement just before the review, the manager might give that event disproportionate weight compared to the entire review period.

How to prevent Recency bias:

Regularly jot down notes about employee performance throughout the review period rather than relying on memory. This provides a more balanced view during evaluations.


Primacy bias

What is Primacy bias?

Primacy bias is the tendency to remember and give more weight to the first pieces of information received about someone. Often forming a “first impression.”

Example of Primacy bias:

When an employee had a rough start at the beginning of the review period but improved over time. The initial impression might dominate the manager’s overall assessment.

How to prevent Primacy bias:

Regular performance check-ins can help to keep evaluations updated. It’s essential to be open to changing first impressions based on new data.

Affinity bias

What is Affinity bias?

Affinity bias is the unconscious tendency to get along with others who are like us. It’s what makes us feel “at home” or familiar with people who have similar backgrounds.

Example of Affinity bias:

In a performance review, a manager might unduly favour an employee who shares similar hobbies, comes from the same region, or attended the same university. Ignoring objectivity.

How to prevent Affinity bias:

Ensure that performance metrics are objective and standardised. Regularly self-reflect and challenge whether personal feelings about an individual are influencing the review.

Similar-to-me bias (or Similarity Bias)

What is Similar-to-me bias?

This bias occurs when evaluators prefer individuals who resemble themselves in some manner, whether it’s by background, beliefs, or experiences.

Example of Similar-to-me bias:

A manager, who prides themselves on their analytical skills, might favour employees who approach problems similarly, even if different approaches might be equally effective.

How to prevent Similar-to-me bias:

Encourage diversity of thought and be aware of the value different perspectives bring. Ensure that reviews consider the results achieved and not just the methods used.

Gender bias

What is Gender bias?

Gender bias involves favouring one gender over another, often because of deep-rooted stereotypes or societal norms.

Example of Gender bias:

During a review, a manager might question the leadership abilities of a female employee not based on her actual performance, but because of unconscious beliefs about gender roles.

How to prevent Gender bias:

Actively challenge and address stereotypes. Use gender-neutral performance metrics and ensure that feedback is based on evidence and not assumptions related to gender. Using performance management software like PerformanceHub can really help. Often, such software has an ability to filter reports on gender. And can perform gender based analysis.

Stereotype bias

What is Stereotype bias?

Stereotypes are overgeneralised beliefs about a particular group of people, leading to biased judgments.

Example of Stereotypes:

A manager might assume an older employee is not as tech-savvy, even if their actual performance and skills show otherwise.

How to prevent Stereotypes:

Treat each employee as an individual, basing evaluations on actual performance rather than assumptions. Engage in continuous learning about unconscious biases.

Horns effect bias

What is Horns effect bias?

The opposite of the Halo effect; a single negative trait influences our perception of someone’s other unrelated characteristics.

Example of Horns effect bias:

An employee might have made a notable mistake early in the year, and even if they’ve performed excellently afterwards, that one error is still clouding the manager’s judgment.

How to prevent Horns effect bias:

Focus on the bigger picture and evaluate performance across multiple metrics. Regular feedback and check-ins can help in keeping evaluations updated.

Leniency bias

What is Leniency bias?

This is the tendency to evaluate people or situations more favorably than is warranted.

Example of Leniency bias:

Wanting to avoid conflict, a manager might rate all their employees as “above average”, even when some clearly need areas of improvement.

How to prevent Leniency bias:

Be honest and transparent in evaluations, focusing on both strengths and areas for improvement. Using standardised evaluation metrics can help maintain objectivity.

Central tendency bias

What is Central tendency bias?

The inclination to avoid extreme judgments and rate people or situations as “average”.

Example of Central tendency bias:

During performance reviews, a manager might give most employees a “satisfactory” rating to avoid making tough decisions, even if some employees deserve higher or lower ratings.

How to prevent Central tendency bias:

Using a broader range of ratings and focusing on evidence-based evaluations can help. Regularly revisiting and calibrating the understanding of what constitutes “average” can also be beneficial.

Spill-over bias

What is Spill-over bias?

Spill-over bias occurs when past performance or events influence the current assessment of an individual or situation.

Example of Spill-over bias:

If an employee had a significant accomplishment the previous year, a manager might overlook areas they underperformed in this year because of the lingering positive impression.

How to prevent Spill-over bias:

Focus on the present evaluation period. Regularly document performance metrics and ensure feedback sessions are based on current events and performances.

Self-rater bias

What is Self-rater bias?

Self-rater bias occurs when individuals evaluate themselves differently compared to an external observer, often seeing themselves in a more positive light.

Looking at nearly 100k appraisals in PerformanceHub, we can see that 72% of the time, the manager’s performance ratings agrees with the employee’s self assessment. And that employees tend to self rate slightly higher than a manager’s rating. This is a typical distribution curve. Negative number show where a manager rates higher than the self assesment.

Manager vs Self Assessment rating distribution

Example of Self-rater bias:

An employee might rate themselves highly in teamwork during a self-assessment, but peers and managers might have noticed they tend to work more independently and not collaborate as effectively.

How to prevent Self-rater bias:

Incorporate 360-degree feedback processes, where feedback is gathered from peers, subordinates, and superiors. This provides a more holistic view and can counterbalance self-rater biases.

Expediency bias

What is Expediency bias?

Expediency bias involves making decisions based on what’s easiest or most convenient rather than what’s most accurate or appropriate.

Example of Expediency bias:

A manager, because of a tight schedule, might rush through performance reviews, relying on vague memories or surface-level impressions rather than a thorough evaluation of an employee’s work.

How to prevent Expediency bias:

Allocate appropriate time for each performance review. Utilise tools and processes that simplify the collection and evaluation of performance data to ensure thoroughness.

Idiosyncratic rater bias

What is Idiosyncratic rater bias?

This bias reflects individual personal preferences based on their own unique experiences and views, which aren’t shared by others.

Example of Idiosyncratic rater bias:

A manager might particularly value punctuality because of their personal upbringing and unduly penalise an employee for occasional tardiness, even if it doesn’t impact their actual job performance.

How to prevent Idiosyncratic rater bias:

Utilise standardised evaluation criteria that are shared and understood by all evaluators. Training on bias awareness can also help highlight and mitigate individual biases.

Law of small numbers bias

What is Law of small numbers bias?

This bias involves drawing conclusions from a limited set of data, or assuming that small samples are representative of the larger population.

Example of Law of small numbers bias:

A manager might witness an employee struggling in a new role during their first week and conclude they’re not fit for the position, without considering that there could be a learning curve.

How to prevent Law of small numbers bias:

Ensure evaluations are based on a comprehensive set of data over a substantial period. Recognise the variability and give time for patterns to emerge before drawing conclusions.

Uncovering the Patterns and Factors Contributing to Bias

In the realm of performance evaluations and assessments, biases play a prominent role in skewing judgments. These biases can creep in subtly, impacting the fairness and accuracy of evaluations. Organisations can ensure fair evaluations by recognising bias patterns and factors. They can then take proactive steps to make evaluations more objective and equal.


Identifying patterns and trends in biased evaluations

Recognising bias involves understanding repetitive patterns in performance evaluations. Some of the common trends that indicate biased evaluations include:

  • Consistency in Ratings: When a diverse set of employees consistently receive similar ratings regardless of variations in their performances, it’s a red flag. If a department consistently rates all women as “average” while frequently rating men as “outstanding,” it may indicate gender bias.
  • Feedback Vagueness: Feedback that is generic and lacks specificity can often be a sign of bias. Instead of highlighting exact areas of improvement, managers might resort to general comments, indicating they’re not thoroughly evaluating an employee’s performance.
  • Disproportional Negative Feedback: When certain groups or individuals constantly receive negative feedback or are frequently singled out for errors compared to their peers, there’s potential bias in play.

By analysing evaluation data and feedback over time, and across different managers and departments, we can identify patterns of biased evaluations. Employing statistical tools and techniques can further help in pinpointing inconsistent ratings.



Factors that influence bias in performance reviews


1. Personal preferences and stereotypes

Everyone has personal preferences, but when these translate into biased evaluations, it becomes problematic. Stereotypes, often deep-rooted and stemming from societal norms or personal experiences, can influence a manager’s judgment. For instance, assuming that older employees aren’t tech-savvy. Or that someone from a particular country is inherently good or bad at a specific skill is indicative of this bias.


2. Unconscious biases and implicit associations

These are biases that individuals are unaware of, and they happen outside of our control. They are automatic judgments and assessments we make about people and situations based on our background, cultural environment, and personal experiences. A manager thinks they’re gender-neutral but unconsciously prefers male employees due to the link between certain job roles and masculinity.

To tackle unconscious biases, individuals must first become aware of them. Tools like the Implicit Association Test (IAT) can help in recognising these biases.


3. Lack of diverse evaluators

When performance evaluations are conducted by a homogeneous group, there’s a higher likelihood of bias creeping in. A diverse set of evaluators brings in different perspectives, reducing the chance of any single bias dominating the evaluation process. If, for example, all evaluators are from a similar age group, educational background, or ethnicity, they might not fully appreciate the strengths and challenges of employees from diverse backgrounds.

By introducing diversity in the evaluation panel and employing a mix of genders, ages, ethnic backgrounds, and other factors, organisations can ensure a more balanced and holistic assessment process.



In conclusion, bias in performance reviews is a significant issue that can compromise the fairness and accuracy of evaluations. As an HR manager, it is your responsibility to be aware of the common biases that can arise and take proactive measures to address them.

By implementing strategies, utilising performance management software tools, and fostering a culture of fairness, you can ensure that your company’s performance review process promotes equal opportunity and supports the growth and development of all employees. Together, let’s strive for unbiased evaluations that truly reflect the talent and potential within your organisation.

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