The original StackExchange thread is an interesting read. For the job applicant (any job applicant), the problem is always how to make an affirmative case that an employer ought to offer the job to you and not to someone else. The commenters on StackExchange and here on HN are mostly commenting from that perspective, that the job applicant has to figure out how to excel over other job applicants in making a strong case for being hired.

Some comments here are about the issue of how companies should hire in the general case. Because that is a frequently asked question here on HN, and because that has been the subject of much research, I'll recycle some electrons here to provide a FAQ on the general issue. The review article "The Validity and Utility of Selection Models in Personnel Psychology: Practical and Theoretical Implications of 85 Years of Research Findings"

http://mavweb.mnsu.edu/howard/Schmidt%20and%20Hunter%201998%...

sums up, current to 1998, much of the HUGE peer-reviewed professional literature on the industrial and organizational psychology devoted to business hiring practices. There are many kinds of hiring screens, such as resume reviews for job experience, telephone interviews, in-person interviews, checks for academic credentials, and so on. There is much published study research on how job applicants perform after they are hired in a wide variety of occupations.

The overall summary of the industrial psychology research in reliable secondary sources is that two kinds of job screening procedures work reasonably well (but only about at the 0.5 level, standing alone). One is a general cognitive ability test (an IQ-like test, such as the Wonderlic personnel screening test). Another is a work-sample test, where the applicant does an actual task or group of tasks like what the applicant will do on the job if hired. Each of these kinds of tests has about the same validity in screening applicants for jobs, with the general cognitive ability test better predicting success for applicants who will be trained into a new job. Neither is perfect (both miss some good performers on the job, and select some bad performers on the job), but both are better than anything else that has been tested in rigorous research, across a wide variety of occupations. So if you are hiring for your company, it's a good idea to think about how to build a work-sample test into all of your hiring processes.

For legal reasons in the United States (the same consideration does not apply in other countries), it is difficult to give job applicants a straight-up IQ test (as was commonplace in my parents' generation) as a routine part of a hiring process. The Griggs v. Duke Power, 401 U.S. 424 (1971) case in the United States Supreme Court

http://scholar.google.com/scholar_case?case=8655598674229196...

held that cognitive ability tests used in hiring that could have a "disparate impact" on applicants of some protected classes must "bear a demonstrable relationship to successful performance of the jobs for which it was used." In other words, a company that wants to use a test like the Wonderlic, or like the SAT, or like the current WAIS or Stanford-Binet IQ tests, in a hiring process had best conduct a specific validation study of the test related to performance on the job in question. Some companies do the validation study, and use IQ-like tests in hiring. Other companies use IQ-like tests in hiring and hope that no one sues (which is not what I would advise any company). Note that a brain-teaser-type test used in a hiring process might be illegal if it can be shown to have disparate impact on some job applicants and is not supported by a validation study demonstrating that the test is related to successful performance on the job. Companies outside the United States are regulated by different laws.