Q1. "What is the difference between reliability and validity?  Are they related?”

The distinction between reliability and validity lies in their focus and implications in research (Schuler et al., 1993).  Reliability refers to the consistency and stability of research findings across repeated measurements, whereas validity emphasises the accuracy and truthfulness of the results concerning the research question (Gatewood et al., 2016).  Although separate concepts, reliability and validity are interconnected, as both are crucial for ensuring the credibility of research outcomes (Cook et al., 2006).  A study can be reliable without validity if it consistently yields inaccurate results (Kaplan et al., 2017).  However, valid research must also be reliable, as the precise findings must be consistent across measurements (Cohen et al., 2021).  Consequently, it is essential to meticulously consider and manage factors influencing reliability and validity, such as bias and confounding variables, to ensure the credibility and applicability of research findings (Pulakos, 2005).


  • Cohen, R.J., Schneider, W.J., & Tobin, R. (2021). Psychological Testing and Assessment: An Introduction to Tests and Measurement (10th ed.). McGraw Hill.
  • Cook, D.A. & Beckman, T.J. (2006). Current concepts in validity and reliability for psychometric instruments: Theory and application. The American Journal of Medicine, 119(2), 166.e7-166.e16.  https://doi.org/10.1016/j.amjmed.2005.10.036
  • Gatewood, R.D., Felid, H.S., & Barrick, M.R. (2016). Human Resource Selection (8th ed.). Cengage Learning.
  • Kaplan, R.M., & Saccuzzo, D.P. (2017). Psychological Testing: Principles, Applications, and Issues (9th ed.). Wadsworth Publishing.
  • Pulakos, E.D. (2005). Selection Assessment Methods: A Guide to Implementing Formal Assessments to Build a High-Quality Workforce. Society for Human Resource Management.
  • Schuler, H., Farr, J.L., & Smith, M. (1993). Personnel Selection and Assessment: Individual and Organisational Perspectives. Psychology Press.

Q2. "According to the Equality Act of 2010 (in UK employment law), what is a 'protected characteristic', and why is it generally unlawful to discriminate against such characteristics?"

A “protected characteristic” refers to a trait or attribute safeguarded under the UK’s Equality Act 2010 in employment law (Equality Act 2010).  The Equality Act 2010 defines nine protected characteristics: age, disability, gender reassignment, marriage and civil partnership, pregnancy and maternity, race, religion or belief, sex, and sexual orientation (Equality Act 2010).

The primary reason why it is generally unlawful to discriminate against protected characteristics is to promote a fair, inclusive, and equal society (ACAS, 2020).  Discrimination based on protected characteristics can lead to adverse outcomes, such as social exclusion, unequal opportunities, and a lack of diversity in various sectors (Noon, 2010).  By making it unlawful to discriminate, the Equality Act 2010 seeks to eliminate these negative consequences, fostering a more equitable and harmonious society (Hoque & Noon, 2004).

However, there are certain circumstances when it is lawful to discriminate based on protected characteristics (Hepple et al., 2000).  These situations are known as exceptions or justifiable discrimination and are typically allowed when there is a genuine occupational requirement or a genuine need for discrimination to occur (McCrudden, 2004).  One example would be an occupational requirement, where, in some cases, it may be necessary for an individual to possess a particular protected characteristic to perform a specific job effectively (e.g., a woman’s refuge may require a female support worker to ensure the privacy and comfort of its clients) (McCrudden, 2004).  Another example could be age discrimination, where, in some cases, it may be lawful to discriminate on age if the bias can be objectively justified (e.g., employers may set a maximum age for specific roles, such as air traffic controllers or pilots, due to safety concerns) (Loretto & White, 2006).


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