Businessman performing shell game scamMany of us in the trade may have been surprised to hear the announcement from Google SVP of People, Laszlo Block, that their famous brainteaser questions, such as, “How many golf balls can you fit into an airplane? “ or “How many gas stations are there in Manhattan?” are in fact a waste of time. Yes, it seems that Google did its own exhaustive “big data’” analysis and found that these brainteaser questions don’t “actually predict anything”, and they primarily serve to “make the interviewers look smart”.

The good news is that Google’s big data studies also helped it to reveal what actually works, (for the company)/ This was structured behavioral interviewing where: 1) you have a standardized questionnaire for everyone and 2) you incorporate behavioral questions that require interviewees to recollect real examples of their conduct in certain situations, rather than just suggesting how they might behave hypothetically. Of course, these questions have been the mainstay of many hiring processes for some time now.

But, since the topic of assessment tools is on the table, I also thought it would be a good time to take a look at what the most reliable assessment tools are, and which are thought to have the most predictive validity, based on studies by Beardwell et all 2004 and the CIPD 2007. You can find these below in rank order of their reliability.

1. Assessment Centers (Predict Validity 0.68)

This is by far the most reliable selection method, yet it is used by only 47 percent of respondents, which is understandable due to the high administrative costs of developing and running an assessment center. Still, if you are hiring in volume for a particular role, an assessment center may well be worth the investment for the increased return in predictive accuracy.

2. Structured Interviews (Predict Validity 0.62)

Being used by 88 percent of respondents, structured interviews are the second most popular assessment tool and they are the second most valid form of assessment – and due to the relatively low administrative burden, compared to assessment centers, they are clearly the most pragmatic option for most businesses most of the time.

3.Work Samples (Predictive accuracy 0.55)

These are the third most popular assessment tool, being used by 80 percent of respondents and they are the third most reliable assessment tool. Work samples, be that code samples, design portfolios, or published articles, etc., are a very pragmatic, cost effective and reliable form of assessment.

4. Ability Test (Predictive accuracy 0.54)

Ability tests, or attainment tests, also have good levels of predictive validity and are the fourth most popular form of assessment and they can be quite an affordable tool. This means they are potentially a very pragmatic and sensible addition to your assessment tool arsenal.

It’s now that we start reaching the problematic areas in terms of assessment tools, for example, personality questionnaires have a predictive accuracy of just 0.38 and yet are used by 56 percent of respondents. Arguably, these should be used as a back up tool to help confirm findings from the more reliable tools above.

Next, at 31% predictive validity, come unstructured interviews or chats which should arguably be avoided altogether given their low levels of reliability. It’s worrying then that these 92 percent of respondents are making use of this tool in the hiring process.

And last AND least are employment references with just 0.13 predictive validity and used by less than half of respondents. But, without doubt, references have their place in terms of confirming facts and background checking, but it seems they don’t add much value to the candidate assessment process in terms of predicting performance, where they are at best a tertiary assessment method.

In pragmatic terms, these assessment tools are, of course, not mutually exclusive and ideally you might combine two or more of these assessment methods to increase the overall predictive validity of your hiring process.



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