An interview protocol is a structured approach to candidate evaluation, designed to ensure fairness and consistency across all applicants. The core challenge is identifying the appropriate number of questions that efficiently gather sufficient data about a candidate’s suitability. Too few questions risk failing to capture a person’s full abilities, while too many can lead to diminished returns and a poor candidate experience. Designing an effective selection process requires balancing the need for data depth with practical constraints of time and attention.
Why the Number of Questions Impacts Interview Validity
The quantity of questions directly influences both the reliability and the predictive validity of the interview process. Asking too few questions results in an insufficient sample of the candidate’s behavior, leading to low reliability. If only one question addresses a major job requirement, the resulting score may be an inconsistent measure of that ability, making accurate comparison difficult.
Conversely, too many questions often decrease the quality of data collected toward the end of the session. As the interview extends, interviewers may suffer from cognitive fatigue, resulting in rushed evaluations and less consistent scoring. This effect introduces error and lowers the overall validity because scoring criteria cannot be applied uniformly. The goal is to maximize predictive power without reaching diminishing returns, where additional questions consume time without providing new, relevant information.
Determining Necessary Coverage Based on Job Competencies
Determining the ideal number of questions begins with a thorough job analysis that identifies the Knowledge, Skills, Abilities, and Other characteristics (KSAOs) required for success. The protocol’s question count must be derived directly from the distinct, high-priority competencies that need assessment. This foundational mapping ensures every question serves a specific, measurable purpose related to the job.
A robust protocol allocates multiple questions to each major competency to ensure reliable coverage and reduce the impact of an isolated weak answer. For competencies significant to job performance, dedicating two to three questions to that area is common practice. This allows the interviewer to sample the candidate’s experience from different angles, providing a more comprehensive evaluation score. The total question count is an outcome of the number of competencies selected and the necessary depth of coverage assigned to each.
The Psychological Impact of Interview Duration
Time constraints limit the effective number of questions asked in a single interview session. Because both parties experience cognitive load, an effective structured interview generally falls within a 45- to 60-minute window. Beyond this duration, the quality of information exchanged deteriorates as fatigue sets in.
Interviewers must actively listen, process complex information, evaluate responses against predetermined criteria, and formulate follow-up probes simultaneously. This intense cognitive effort becomes unsustainable over an extended period, leading to rushed scoring and declining attentiveness. A protocol must prioritize depth of answer over breadth of questioning to respect these psychological limitations, ensuring candidates have adequate time to provide detailed, high-quality responses, often using the STAR method.
Maximizing Data Collection Through Question Design
The number of questions becomes less important when the focus shifts to the quality and structure of each individual question. Highly structured questions, such as behavioral and situational prompts, maximize the data yield from a single response, replacing the need for multiple, less-focused inquiries. These questions compel the candidate to provide concrete examples of past actions or hypothetical solutions, which are far more predictive of future job performance than general opinions.
A well-designed behavioral question is crafted to elicit a complete narrative covering a single, defined competency, providing material for a thorough evaluation. This efficiency means fewer total questions are required to achieve the same level of predictive validity compared to a protocol relying on broad, unstructured inquiries. Optimizing question format to be specific and linked to observable behaviors reduces the overall question count without sacrificing the integrity of the selection process.
Practical Benchmarks for Optimal Question Ranges
While the optimal number is customized based on competencies and time, practical benchmarks offer a helpful starting point for protocol design. For a standard structured interview scheduled for 45 to 60 minutes, the most effective range involves asking six to eight comprehensive questions. This allows sufficient time for the candidate to provide detailed, evidence-based answers and for the interviewer to take accurate notes and score responses objectively.
Shorter screening interviews, often 20 to 30 minutes long, should be limited to three to five high-impact questions focused on foundational competencies. The key is ensuring the total time required for candidate responses, plus introductory and closing remarks, fits comfortably within the allotted session. The goal is to gather a high-density data set that directly informs the hiring decision within a practical time frame.
Evaluating and Refining Your Protocol
Once an interview protocol is implemented, its effectiveness must be measured. The initial phase of evaluation involves assessing inter-rater reliability, which measures the consistency of scoring among different interviewers using the protocol. If interviewers consistently assign similar scores to the same responses, it suggests the questions are clear and the evaluation criteria are applied uniformly.
Further refinement requires correlating interview scores with objective, post-hire job performance data. If a particular question or section shows a weak correlation with later success on the job, it signals that the question is not contributing meaningful, predictive information. Refinement might involve removing low-utility questions, consolidating redundant topics, or replacing broad questions with more targeted ones. This ensures the final protocol is lean and predictive.