Bell Curve

Meaning & Definition

Bell Curve

Bell curves, also called Gaussian distributions and normal distributions, are so-called because the line resembles a bell. Bell curves are underpinned by the theory that if you map people’s performance, most will fall into a specific range. Bell curves represent the standard distribution of a rating, result or test score in that the top of the ‘bell’ is the most likely event, with other possible events evenly distributed around the most likely event on both sides.

Frequently Asked Questions (FAQ's)

  1. What does the bell curve signify?

    Bell curves are normal curves that are important to identify financial and economic trends and are widely used to draw a variety of statistics. In the HR domain, they are a tool to measure employee performance and for performance appraisal. The peak of the bell curve depicts the mean, median, and mode of a certain set of data.

  2. What is the bell curve rule?

    The bell curve rule also knows as the 68 95 99 rule implies the following:

    • About 68% of all the data lies within one standard deviation of the mean.
    • Approximately 95% of all the data is within two standard deviations of the mean.
    • Up to 99.7% of the data is within three standard deviations of the mean.
  3. Is the bell curve good or bad?

    Bell curve is both good and bad based on different situations. It is particularly useful for large to very large companies since they have a lot of data to derive insight from, whereas for a small company with about 300 or fewer employees, it is not very helpful. This is because in small firms which have less data, the curve cannot be done properly, and the results are mostly skewed.

    Bell curve is also considered bad on occasions when even though the employee does not fit into the curve, they have to. It is an insensitive approach that ranks the employees.

  4. What are some advantages of bell curve?

    • It helps easily identify top performing employees.
    • The suitability of the employee for a particular job position can be identified.
    • Proper allocation of training needs for each employee can be identified.
  5. What are the demerits of bell curve?

    • It is extremely inflexible.
    • It looks down upon employees as mere data points and thus results in loss of morale.
    • It is not a good fit for small companies.
  6. Why is the bell curve so common?

    It is common for a number of reasons such as:

    • Ease of implementation.
    • It is effective and works in most situations.
    • Most data values are 'mean' values.
    • HRs can easily meet their goal of doing performance appraisals without any major change in existing software.

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