Candidate Assessments in Hiring: How to Choose the Right Methods

Candidate assessments is a broad term and refers to far more selection methods than many people realise. It includes any structured method used to evaluate candidates, such as cognitive ability tests, personality tests, work samples, assessment centres and even interviews.

Each of these methods is designed to measure different attributes. They are not interchangeable, and each provides insight into a different aspect of candidate suitability.

Cognitive ability assessments reflect how quickly someone can understand information, solve problems, and adapt when things change (these come in the forms of numerical, verbal, logical, etc.). These abilities underpin learning speed and problem-solving across most roles and are difficult to infer reliably from CVs.

Personality assessments measure behavioural preferences and working style. They add useful context around how someone is likely to approach work and interact with others.

Situational judgement tests (SJTs) assess how candidates judge and respond to job-related scenarios. They are designed to capture decision-making tendencies in contexts similar to those encountered on the job.

Work samples and job simulations evaluate how candidates perform on representative tasks. These methods focus on observable behaviour rather than inferred capability.

Interviews are a staple for all hiring processes (and rightly so), they explore experience, communication, motivation, and fit. There are two broad types: Unstructured interviews don't follow a strict framework and are closer to a free-flowing conversation, while structured interviews ask all candidates the same questions and assess responses in a more consistent way. We cover the differences in detail in our guide to structured vs unstructured interviews.

Candidate assessment methods differ not just in what they measure, but in the advantages they offer and how well they predict job performance. Some methods are highly scalable and objective, while others provide richer insight but require more time and resource.

The table below compares the most common candidate assessment methods, showing what each measures, how strongly it predicts job performance, and its key strengths.

Predictive accuracy values are correlations from meta-analytic research (e.g. Schmidt & Hunter and subsequent studies) and vary by role, assessment design, and implementation quality. A score of 1.0 would indicate perfect prediction of job performance, so values such as 0.65 for cognitive ability represent a very strong indicator.

Across the research, two methods stand out. Cognitive ability assessments show the strongest single relationship with job performance. Structured interviews are the most effective way to assess experience, motivation, and fit in a consistent and comparable way.

Used together, these methods complement each other well and result in strong predictive power.

Understanding the strengths of different assessment methods is only part of the picture. How effective an assessment is also depends on when it is used in the hiring process.

Early stages of hiring typically involve large applicant pools and limited time. At this point, methods that are objective, scalable, and predictive add the most value. Cognitive ability assessments, often combined with personality assessments, are well suited here because they allow teams to shortlist candidates based on skills and potential rather than background.

Using cognitive ability tests at the start is a much simpler and more effective way to shortlist candidates. They are delivered through a candidate assessment platform, meaning no supervision or manual screening is required. Whether you assess 10 candidates or 10,000, the time investment is effectively the same, and reduces the risk of missing high-potential candidates who might be less polished on paper.

Interviews and work samples work best later on, once the applicant pool is small enough to justify the time-investment. They're much more effective when you are assessing candidates who already meet the baseline requirements - allowing you to explore motivation and fit, rather than discovering gaps in capability within the first few minutes.

A simple rule of thumb:

• Use ability (and personality) assessments to decide who to interview
• Use interviews and work samples to decide who to hire

Candidate assessments are powerful, but many problems arise from how they are applied rather than from the assessments themselves.

Using too many assessments

It's not as simple as adding more assessments to get better data and better decisions. There is a balance to strike. Each additional assessment adds friction for candidates (increasing fatigue and drop-off rates), and beyond a certain point the extra information you gain starts to level off. In practice, a small number of well-chosen assessments is usually more effective.

Using time-intensive methods too early

Structured interviews and work samples are valuable, but they are not designed to shortlist large pools. Using them early makes hiring slower and more resource-intensive than necessary.

Assuming all assessment providers are equal

It is easy to assume that two numerical reasoning tests from different providers will perform in the same way. In practice, assessment quality can vary significantly. Reliability, validity, question design, and whether tests are static or supported by large item banks all affect accuracy and fairness.

The science behind the assessment matters. Choosing a provider with strong psychometric foundations is essential. This is an area we focus on heavily at Test Partnership, our assessment science outlines how our assessments are developed and tested.

Overweighting hard skills in early-career hiring

Early-career candidates often lack fully developed technical skills simply because they have had limited opportunity to build them. Screening heavily for hard skills at this stage can exclude high-potential candidates who would learn quickly on the job. We discuss this in more detail in our evidence-based early-careers hiring strategy.

Measuring the wrong soft skills

Soft skills only add value when they are clearly linked to the role. Measuring generic traits without context can dilute decision-making rather than improve it. Success in certain roles is often underpinned by specific soft skills. For example, customer-facing roles often depend on communication, agreeableness and empathy.

Getting started with candidate assessments doesn't need to be complicated.

It's often wise to start with just one role. Decide what you need to measure to predict success in that role - often this will be a combination of cognitive ability and personality traits. If you are unsure what success in the role looks like in terms of cognitive ability or personality, this is where expert input helps.

From the various data studies and our own experience, cognitive ability assessments are usually most effective as the first screening stage. Using them early allows you to shortlist candidates based on skills and potential, keeping the process focused and saving time for both hiring teams and candidates. You can then use interviews and work samples on your shortlist to add context and make your final decisions.

At Test Partnership, assessments are designed to support this approach. Our ability and personality assessments are scientifically validated, adaptive, and built using large item banks to ensure accuracy, fairness, and a strong candidate experience. Hiring teams can set up assessments quickly, review results clearly, and combine different tests depending on the role.

The next step is to explore specific assessment types in more detail and decide how they fit into your hiring workflow. You can book a free consultation with our business psychologist to understand how candidate assessments could fit into your hiring needs.