Why self-assessment tests are flawed tools

  • 16/07/2015
  • There are three things extremely hard: steel, a diamond, and to know one’s self.  —Benjamin Franklin, 'Poor Richard’s Improved Almanack' (1750)

    Most people think that they can make accurate judgments about their own future behavior and performance. In reality, it is very hard to judge one’s own skills. Research shows us in various ways that self-assessment is a flawed method to measure skills, personality or performance. Even so, in selection and training processes people are still often judged on the basis of their scores in self-assessment tests. 

    • What research proves?

    People overrate themselves. They overestimate the likelihood that they will engage in desirable behaviour and be successful. They are overly optimistic about when they will finish future projects and make judgements about themselves with too much confidence.
    Many people rank themselves as ‘above average’ - for example, on leadership skills - but statistically this is (of course) not possible.
    Self-assessment tests only show a weak correlation between self-rating and actual performance. For intelligence there is only a 0.2-0.3 correlation and for performing complex tasks there is a correlation of just 0.2 in terms of expected versus actual performance.
    It is not only employees but also the CEO’s who are overly confident when making judgments.

    • Why is there such a bias?

    1. Lack of knowledge:

    Often people do not have the necessary knowledge or expertise to assess their competences adequately. In many cases the skills needed to recognize a certain competence are the same as the skills needed to give correct responses. For example, if people do not know what is necessary to be innovative and which factors are important, they will also not be able to make an accurate assessment of their own innovation qualities.

    Research shows that people who perform worse than their colleagues regularly fail to realize just how deficient their performance really is. People are only aware of the solutions which they themselves developed, so that they are not able to make an accurate estimation of their own competence in comparison with the totality of possible options (all the solutions they did not develop).

    2. Measuring weakly defined skills:

    In many domains it is hard to define what it takes to succeed and people tend to believe that they perform above average with skills that are weakly defined. This becomes difficult, for example, when you ask people to rate themselves on innovation, a concept that is not clear for everyone. It seems that everybody has his or her own definition. This makes it harder to accurately judge your own competences.

    3. People neglect their own capabilities

    Even when people have all the information needed to make a good self-assessment, they often fail to make proper use of this information. The quality of their assessments is poorer than what they are theoretically capable of.

    4. People do not compare themselves with others

    When people have information about how others perform, they tend to ignore this information instead of comparing their performance with the performance of their colleagues.

    5. People cannot predict their behaviour in future situations

    People cannot make good predictions about how they will perform in future situations. They are overly optimistic about their own performance, because they fail to make allowance for crucial details or factors that will affect these future situations. However, when you confront them with the possible alternatives or explain the different factors that can play a role, people then tend to be better at predicting what they would do. In this way, you can obtain a more accurate prediction of how people would behave in certain situations.

    6. People think of the best case scenario

    When people think about the ‘most realistic’ scenario, they tend to think about the ‘best case’ instead of the ‘worst-case’. They neglect information they have about how an event may develop into a worst-case scenario.

    7. People ignore past performance

    People tend to ignore the information they have about their own performance in the past. Even if they have experience of a particular task, they are inclined to be overly optimistic and ignore bad judgments made in the past.

    8. People overestimate their own skills

    When the judgments of employees about ‘how good they are at a particular skill’ are compared with ‘how good they really perform with that skill’, research clearly proves that people consistently overestimate their own performance.

    9. People steer the outcome

    Research also shows that some people are aware that they have biased self-perceptions. They tend to show a more positive image of themselves in selection contexts or during self-assessment tests, in order to influence the decision to hire them. These people feel the need to ‘self-enhance’ themselves, so that they can get the job they want. People modify their opinions about themselves for different motives in relation to the goals they want to achieve in a given situation. 

    As a result of all the above, it is reasonable to conclude that the evaluation of certain skills based solely on self-assessment tests is not a good idea. It is important to make people aware of the bias in self-assessment and the heuristics they make. Start using objective and validated assessment formats, such as situational judgment tests (something we will write about in a future post). 




    Dunning, D., Heath, C., &Suls, J. M. (2004). Flawed self-assessment: Implications for health, education, and the workplace. Psychological Science in the Public Interest, 5, 69–106.

    Bollich, K. L., Rogers, K. H., Vazire, S. (2015). Knowing More Than We Can Tell: People Are Aware of Their Biased Self-Perceptions. Personality and Social Psychology Bulletin, 1-12

    Zell, E., Krizan, Z. (2014). Do People Have Insight Into Their Abilities? A Metasynthesis. Perspectives on Psychological Science, 9(2), 111-125

    Diederik Syoen

    Diederik Syoen

    Diederik translated the innovation aspect and the psychological research into the development of a user-friendly and visually attractive test. He not only manages the software team but is also responsible for the marketing of the tool.

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