When Judging Candidates, Less Is More - How Nondiagnostic Information Affects Judgment in the Process of Personnel Selection

Sep 18, 2026

This master’s thesis investigates how nondiagnostic information influences evaluative judgment during personnel selection. Building on findings of a dilution effect—where irrelevant information makes predictions less extreme—the study tests whether judges can disregard obviously irrelevant cues but fail to do so when information seems relevant. Participants (N=145) evaluated the same 15 job candidates under three information conditions. Results show no effect of nondiagnostic information on overall judgment, but seemingly diagnostic information significantly altered candidate rankings and increased variance.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages46

Reading Time1 h 56 min

AccessFree to download

Abstract

Keywords

Acknowledgements

Introduction

Evaluative judgment and human decision limits

Personnel selection as an organizational success factor

Interview use and weak predictive validity

Structured and mechanical decision approaches

Candidate fairness in recruitment processes

Fairness and variability in human judgment

Department of Psychology When judging candidate’s, less is more: How nondiagnostic information affects judgment in the process of personnel selection Vilma Seth Master’s thesis (15 hp) Spring 2022 Supervisor: Martin Bäckström Abstract Previous studies have found what is referred to as a dilution effect of nondiagnostic information when subjects make evaluative judgment tasks of future performance, meaning that the presence of nondiagnostic information makes predictions less extreme. However, a large study recently failed to replicate this effect. The hypothesis of this study is that judges can discard from obviously irrelevant information but fail to do so when the information is seemingly relevant (meaning apparently useful, but without an effect on performance) , and that this will influence both the ranking of the candidates and the amount of variance, or noise, in the evaluations. To measure this the participants (N = 145) were randomly assigned to three different conditions where they judged the same 15 job candidates. In one condition only diagnostic information about the candidates was shared, in the second the participants also received obviously nondiagnostic information (about hobbies, siblings, favourite food and similar) and in the third condition the participants received diagnostic information and seemingly diagnostic information, in the form of personality traits without relation to performance and the candidate’s self-description. The study found that while there was no effect of the nondiagnostic information on judgment, there was a significant effect of the seemingly diagnostic information on the ranking of candidates, as well as on the amount of variance, in judgments of individual candidates. The conclusion is that judges seem able to disregard obviously nondiagnostic information, but are still affected by seemingly diagnostic information, which affects ranking and adds variability. Keywords: dilution effect, personnel selection, recruiting, nondiagnostic information, noise Acknowledgements I want to direct my biggest and warmest thank to my supervisor, Martin Bäckström, who tirelessly have been discussing my various research topics with me, then the experiment design, then the results and the confusing and marvelous laws of statistics. Thank you for your brilliance and your patience. I also want to thank Jenny Heffler and Viktoria Asp at Meritmind for giving me valuable insights into the world of recruiting. When judging candidate’s, less is more: How nondiagnostic information affects judgment in the process of personnel selection When people make evaluative judgments, they tend to combine available information and weigh them against each other to form a judgment or prediction (Brunswik, 1952) . However, an impressive body of research, perhaps most notably the work of Tversky and Kahneman, tells us that humans unfortunately are quite unreliable decision makers (Tversky & Kahneman, 1973) and that we are painfully ignorant of our own shortcomings (Kahneman, 2011) . This deficit of the human mind has many implications for us as a species, but for the purpose of this study we will focus on the effects it has on personnel selection. Finding and attracting talent is considered one of the most important success factor for organizations today (Boston Consulting Group, 2007) . And attaining talent is expensive, a 2016 report from SHRM (the Society for Human Resource Management) states that median cost per non-executive hire is $1633, while the average cost is $4425 (N = 488) (SHRM, 2016) . A German study calculated the cost to an average of 8 weeks wages, roughly € 4700 (Muehlemann & Pfeifer, 2016). But part from the cost of hire, there is additional costs to making the wrong hiring decision, that can widely overshadow the direct costs: costs of turnover, low efficiency cost, and lost revenue from the not-recruited better fit employee (O’Connell & Kung, 2007). Conclusively there is a clear

FAQs

What is the main research question of the thesis?

The thesis examines how nondiagnostic information affects evaluative judgment in personnel selection, particularly whether seemingly relevant but non-influential information changes rankings and judgment variability.

How was the study designed to test this hypothesis?

A total of 145 participants were randomly assigned to three conditions and judged the same 15 job candidates, receiving different types of diagnostic, obviously nondiagnostic, or seemingly diagnostic information.

What were the key findings about nondiagnostic versus seemingly diagnostic information?

Nondiagnostic information did not affect judgment. However, seemingly diagnostic information significantly affected candidate rankings and increased variance, adding variability to evaluations.

Sep 18, 2026

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