The case for structured interviewing isn't opinion or best practice instinct. It's one of the most well-evidenced conclusions in industrial-organisational psychology — backed by decades of research, dozens of meta-analyses, and millions of data points.

Validity: The Key Metric

The primary way researchers measure the quality of a selection method is validity — specifically, criterion validity: how well does this method predict actual job performance? The correlation coefficient (r) ranges from 0 (no predictive value) to 1 (perfect prediction). In practice, anything above 0.4 is considered high for a selection method.

The Schmidt & Hunter (1998) Meta-Analysis

The landmark study by Frank Schmidt and John Hunter examined 85 years of personnel selection research. Their findings on interviews:

For context, years of work experience had a validity of 0.18, and reference checks 0.26. The structured interview outperformed most commonly used selection tools.

Why the Gap? Two Key Mechanisms

Research identifies two reasons structured interviews are more valid:

  1. Standardisation reduces measurement error. When every candidate gets the same questions, you're measuring the same construct across all candidates. Random variation in question difficulty is eliminated.
  2. Scoring rubrics reduce evaluator inconsistency. Behavioural anchors constrain the range of possible interpretations. Two interviewers using the same rubric produce more similar scores than two interviewers with only a number scale.
Key insight from Campion et al. (1997) A comprehensive review identified 15 features that increase the validity of structured interviews. The most impactful: asking job-related questions, using behavioural questions, having a standardised scoring system, and training interviewers on evaluation standards.

Inter-Rater Reliability

Structured interviews also produce higher inter-rater reliability — different interviewers give more similar scores. In unstructured interviews, the same candidate assessed by two different interviewers can receive very different ratings. Structured interviews with defined rubrics reduce this variance substantially.

Adverse Impact

One important finding: structured interviews produce less adverse impact — smaller differences in scores between demographic groups — than unstructured ones. This matters for legal compliance and for diversity outcomes.

The Practical Case

If a hiring decision takes 30 minutes to execute and the person hired either does or doesn't perform well for 2+ years, the ROI of investing in a properly structured interview is enormous. A scorecard that takes 30 seconds to generate and saves even one bad hire per year pays for itself many times over.

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