Chapter 3 The Economic Pressure to Partition
Different levels of IQ influence job performance, with education often being considered the main reason people with higher IQs occupy better positions. High test scores can lead individuals to prestigious colleges and professional schools, resulting in enhanced job opportunities. While education is essential, research indicates that cognitive ability, as shown by IQ, is directly linked to job productivity across various professions, including both skilled and unskilled jobs.
Employees with higher IQs tend to be more productive, and this trend continues over time. IQ scores are more effective predictors of job performance than other hiring methods like interviews or reference checks. An economy that allows hiring based on intelligence tests becomes more efficient, but laws have prohibited the use of such tests since 1971, which may lead to significant economic losses.
Three theories explain the connection between cognitive ability and job status. First, education may reflect the skills needed in the workplace. Second, job credentials might serve primarily as filters for IQ. Third, cognitive ability itself may hold market value, meaning intelligence is critical for productivity in all job types. Overall, intelligence plays a crucial role in achievement and success in the workplace, suggesting businesses should consider IQ in their hiring practices.
The Received Wisdom
Test scores, like the SAT, have a limited connection to what students achieve in life after school. For instance, a student might score poorly on the SAT but still pursue a successful career in business or politics. The belief that test scores strongly predict future success is often exaggerated, with many factors influencing a person's life beyond these scores. Specifically, the correlation between test scores and future achievements, like income, can be weak or even negative among graduates from prestigious universities.
The concept of correlation is important when discussing the relationship between intelligence and job performance. Correlation coefficients can range from -1 to +1, indicating the strength and direction of a relationship. In social sciences, strong correlations are rare, often ranging between .2 and .6. A correlation of .33, for example, indicates a significant but modest relationship between education and income. This means that while education generally leads to higher income, there are many exceptions where individuals with less education earn more.
Factors such as "restriction of range" can affect correlations in specific job settings. For instance, in the NFL, all players are heavy, so weight may not correlate well with performance among those players. However, in a general population, weight and performance might show a strong relationship.
It's also essential to differentiate between using test scores as hiring criteria and recognizing their weak correlation with job abilities. Various studies have shown inconsistent results regarding the predictive power of test scores for job performance. A Supreme Court ruling established that job tests must relate directly to job skills, pushing employers to focus on specific abilities relevant to the position rather than general intelligence measures. This approach aligns with the idea that qualifications should reflect the skills necessary for a job, emphasizing that criteria for hiring should be relevant to the job itself.
The Received Wisdom Overturned
New research has shown that common beliefs about hiring practices were wrong. Studies have found that tests measuring general intelligence can better predict how well someone will do a job compared to more specific tests. This suggests that mental tests are linked to job performance mainly through a general cognitive ability factor called "g." Experts' views have changed largely because of a method called meta-analysis, which combines results from many studies, revealing stronger connections between intelligence and job performance than before.
The Link Between Cognitive Ability and Job Performance
There is a clear connection between cognitive ability, often measured by IQ, and job performance. Job performance can vary significantly, and this variation matters both in workplaces and everyday situations. For example, the difference in effectiveness between top and lower-performing workers can have noticeable economic impacts. Various ways measure job performance, like productivity rates or evaluations from supervisors. Research shows an average correlation of about 0.4 between intelligence tests and job performance, which is known as validity. This correlation tends to be higher for complex jobs compared to simpler tasks.
Studies have examined job performance across many fields, finding varying degrees of validity. For instance, managers typically have a higher validity of around 0.53, while workers in trades have a validity of about 0.46. One comprehensive analysis on the General Aptitude Test Battery showed an average validity of 0.45, with only a few job categories, like unskilled labor, scoring lower. The military also offers a robust dataset because it tracks cognitive tests and training success, reflecting a strong validity of about 0.62 across job categories. Some debates exist about validity estimates, but omitting range restrictions can lead to lower correlations that misinterpret the link between cognitive ability and job performance.
The Reasons for the Link Between Cognitive Ability and Job Performance
Job performance and cognitive ability are closely related. Research shows that people with higher general intelligence (g) tend to perform better at their jobs, including in specialized fields like surgery. While some may believe that job-specific skills are the most important, studies indicate that general cognitive ability is actually a stronger predictor of how well someone will do in their job.
For instance, in the military, a study involving over 78,000 Air Force personnel found that g explained a significant part of how well recruits did in their training. The same pattern applies to civilian jobs. One study showed that job performance in twenty-eight different occupations was related to general intelligence just as much as to specific skills. In fact, tests measuring general intelligence often predict job success better than tests made to assess job-related skills.
The idea is that even in simple jobs, cognitive ability plays a big role. For example, a busboy might not need a high IQ to do basic tasks, but a smart busboy can prioritize work, remember orders, and handle multiple tasks better than an average busboy. This shows that intelligence helps with problem-solving and decision-making in all kinds of jobs. As job complexity increases, the benefits of having a higher general intelligence become even clearer. Therefore, it's important for employers to focus on general cognitive ability when choosing candidates for various positions.
Does More Experience Make Up for Less Intelligence?
Experience can help close the productivity gap between employees with differing intelligence levels, but the effect is limited. Initially, more intelligent workers tend to be more productive, especially at the start of a job. As less intelligent workers gain experience, they improve quickly at first, but this improvement levels off over time. However, intelligence continues to play a consistent role in job performance. Research shows that differences in productivity due to intelligence do not significantly diminish, even after many years on the job. While there is some evidence of convergence in academic settings, it is less evident in job performance evaluations. Overall, hiring less intelligent workers may result in sustained productivity costs throughout their employment.
Test Scores Compared to Other Predictors of Productivity
Cognitive test scores are better predictors of job productivity than other methods like job interviews, reference checks, or college transcripts. A study shows test scores have a validity of .53 for higher-complexity jobs, making them the most reliable measure. Even using a more modest estimate of .4, test scores still outperform other predictors, while interviews have a low validity of .14. Choosing candidates based on test scores typically results in more productive employees compared to relying on any single alternative method.
The Difference Intelligence Makes
The connection between intelligence and job performance is important, with a correlation of about .4. While this may seem low, it really matters for more complex jobs. In simpler jobs, small differences in test scores might not affect hiring decisions, but in more challenging roles, cognitive ability can greatly improve productivity.
When looking at the economic value of intelligence, we can see that hiring someone with higher cognitive skills can lead to significant increases in productivity. For example, hiring a top-performing employee in certain jobs can result in a salary difference of about 40% compared to an average employee. This difference is much larger in complex jobs like engineering than in simpler ones like assembly-line work.
For specific roles, such as dentists and receptionists, the value of hiring more skilled workers shows even bigger disparities. For instance, the difference in annual earnings between an average dentist and a top one can be around $50,000, while for a receptionist, it might only be about $3,750. This shows how much more valuable it is to hire skilled individuals in jobs that require advanced abilities.
The usefulness of intelligence tests in hiring also depends on how many applicants there are. The more candidates available, the more valuable testing becomes, as it can help employers find better workers. Even if the correlation between test scores and job success is low, it can still be beneficial to use tests when there are only a few job openings.
Not using intelligence tests can result in significant losses to the economy, with estimates ranging from $80 billion to $13 billion each year. Other factors like education and family connections may relate to intelligence but do not replace the benefits of intelligence tests.
In competitive job markets, where many applicants are highly qualified, having a good selection process is crucial. Small differences in cognitive skills can lead to large economic impacts, highlighting the need for careful hiring in top positions.
Why Partitioning Is Inevitable
Most jobs in civilian and military fields can be predicted by a person's IQ, with a general accuracy of about 0.4. This means that cognitive ability is a strong sign of job performance. More difficult jobs show an even stronger link to intelligence. A specific case is from New York City in 1939, where almost 30,000 men took tests to join the police force. They were chosen based on their scores, especially on the mental part of the test. Those selected ended up doing very well in their careers and achieved high ranks in the police department, with some even becoming leaders in the field.
Using tests to hire workers can be a smart financial decision for companies. Even tests that are not very strong predictors can still help if only a few applicants are hired or if workers' productivity varies a lot. Even if there are rules against using intelligence tests, knowing about a candidate's intelligence is still important. Employers naturally look for the smartest candidates to build a better workforce, and this focus on intelligence affects how much workers are paid.
Different levels of IQ influence job performance, with education often being considered the main reason people with higher IQs occupy better positions. High test scores can lead individuals to prestigious colleges and professional schools, resulting in enhanced job opportunities. While education is essential, research indicates that cognitive ability, as shown by IQ, is directly linked to job productivity across various professions, including both skilled and unskilled jobs.
Employees with higher IQs tend to be more productive, and this trend continues over time. IQ scores are more effective predictors of job performance than other hiring methods like interviews or reference checks. An economy that allows hiring based on intelligence tests becomes more efficient, but laws have prohibited the use of such tests since 1971, which may lead to significant economic losses.
Three theories explain the connection between cognitive ability and job status. First, education may reflect the skills needed in the workplace. Second, job credentials might serve primarily as filters for IQ. Third, cognitive ability itself may hold market value, meaning intelligence is critical for productivity in all job types. Overall, intelligence plays a crucial role in achievement and success in the workplace, suggesting businesses should consider IQ in their hiring practices.
The Received Wisdom
Test scores, like the SAT, have a limited connection to what students achieve in life after school. For instance, a student might score poorly on the SAT but still pursue a successful career in business or politics. The belief that test scores strongly predict future success is often exaggerated, with many factors influencing a person's life beyond these scores. Specifically, the correlation between test scores and future achievements, like income, can be weak or even negative among graduates from prestigious universities.
The concept of correlation is important when discussing the relationship between intelligence and job performance. Correlation coefficients can range from -1 to +1, indicating the strength and direction of a relationship. In social sciences, strong correlations are rare, often ranging between .2 and .6. A correlation of .33, for example, indicates a significant but modest relationship between education and income. This means that while education generally leads to higher income, there are many exceptions where individuals with less education earn more.
Factors such as "restriction of range" can affect correlations in specific job settings. For instance, in the NFL, all players are heavy, so weight may not correlate well with performance among those players. However, in a general population, weight and performance might show a strong relationship.
It's also essential to differentiate between using test scores as hiring criteria and recognizing their weak correlation with job abilities. Various studies have shown inconsistent results regarding the predictive power of test scores for job performance. A Supreme Court ruling established that job tests must relate directly to job skills, pushing employers to focus on specific abilities relevant to the position rather than general intelligence measures. This approach aligns with the idea that qualifications should reflect the skills necessary for a job, emphasizing that criteria for hiring should be relevant to the job itself.
The Received Wisdom Overturned
New research has shown that common beliefs about hiring practices were wrong. Studies have found that tests measuring general intelligence can better predict how well someone will do a job compared to more specific tests. This suggests that mental tests are linked to job performance mainly through a general cognitive ability factor called "g." Experts' views have changed largely because of a method called meta-analysis, which combines results from many studies, revealing stronger connections between intelligence and job performance than before.
The Link Between Cognitive Ability and Job Performance
There is a clear connection between cognitive ability, often measured by IQ, and job performance. Job performance can vary significantly, and this variation matters both in workplaces and everyday situations. For example, the difference in effectiveness between top and lower-performing workers can have noticeable economic impacts. Various ways measure job performance, like productivity rates or evaluations from supervisors. Research shows an average correlation of about 0.4 between intelligence tests and job performance, which is known as validity. This correlation tends to be higher for complex jobs compared to simpler tasks.
Studies have examined job performance across many fields, finding varying degrees of validity. For instance, managers typically have a higher validity of around 0.53, while workers in trades have a validity of about 0.46. One comprehensive analysis on the General Aptitude Test Battery showed an average validity of 0.45, with only a few job categories, like unskilled labor, scoring lower. The military also offers a robust dataset because it tracks cognitive tests and training success, reflecting a strong validity of about 0.62 across job categories. Some debates exist about validity estimates, but omitting range restrictions can lead to lower correlations that misinterpret the link between cognitive ability and job performance.
The Reasons for the Link Between Cognitive Ability and Job Performance
Job performance and cognitive ability are closely related. Research shows that people with higher general intelligence (g) tend to perform better at their jobs, including in specialized fields like surgery. While some may believe that job-specific skills are the most important, studies indicate that general cognitive ability is actually a stronger predictor of how well someone will do in their job.
For instance, in the military, a study involving over 78,000 Air Force personnel found that g explained a significant part of how well recruits did in their training. The same pattern applies to civilian jobs. One study showed that job performance in twenty-eight different occupations was related to general intelligence just as much as to specific skills. In fact, tests measuring general intelligence often predict job success better than tests made to assess job-related skills.
The idea is that even in simple jobs, cognitive ability plays a big role. For example, a busboy might not need a high IQ to do basic tasks, but a smart busboy can prioritize work, remember orders, and handle multiple tasks better than an average busboy. This shows that intelligence helps with problem-solving and decision-making in all kinds of jobs. As job complexity increases, the benefits of having a higher general intelligence become even clearer. Therefore, it's important for employers to focus on general cognitive ability when choosing candidates for various positions.
Does More Experience Make Up for Less Intelligence?
Experience can help close the productivity gap between employees with differing intelligence levels, but the effect is limited. Initially, more intelligent workers tend to be more productive, especially at the start of a job. As less intelligent workers gain experience, they improve quickly at first, but this improvement levels off over time. However, intelligence continues to play a consistent role in job performance. Research shows that differences in productivity due to intelligence do not significantly diminish, even after many years on the job. While there is some evidence of convergence in academic settings, it is less evident in job performance evaluations. Overall, hiring less intelligent workers may result in sustained productivity costs throughout their employment.
Test Scores Compared to Other Predictors of Productivity
Cognitive test scores are better predictors of job productivity than other methods like job interviews, reference checks, or college transcripts. A study shows test scores have a validity of .53 for higher-complexity jobs, making them the most reliable measure. Even using a more modest estimate of .4, test scores still outperform other predictors, while interviews have a low validity of .14. Choosing candidates based on test scores typically results in more productive employees compared to relying on any single alternative method.
The Difference Intelligence Makes
The connection between intelligence and job performance is important, with a correlation of about .4. While this may seem low, it really matters for more complex jobs. In simpler jobs, small differences in test scores might not affect hiring decisions, but in more challenging roles, cognitive ability can greatly improve productivity.
When looking at the economic value of intelligence, we can see that hiring someone with higher cognitive skills can lead to significant increases in productivity. For example, hiring a top-performing employee in certain jobs can result in a salary difference of about 40% compared to an average employee. This difference is much larger in complex jobs like engineering than in simpler ones like assembly-line work.
For specific roles, such as dentists and receptionists, the value of hiring more skilled workers shows even bigger disparities. For instance, the difference in annual earnings between an average dentist and a top one can be around $50,000, while for a receptionist, it might only be about $3,750. This shows how much more valuable it is to hire skilled individuals in jobs that require advanced abilities.
The usefulness of intelligence tests in hiring also depends on how many applicants there are. The more candidates available, the more valuable testing becomes, as it can help employers find better workers. Even if the correlation between test scores and job success is low, it can still be beneficial to use tests when there are only a few job openings.
Not using intelligence tests can result in significant losses to the economy, with estimates ranging from $80 billion to $13 billion each year. Other factors like education and family connections may relate to intelligence but do not replace the benefits of intelligence tests.
In competitive job markets, where many applicants are highly qualified, having a good selection process is crucial. Small differences in cognitive skills can lead to large economic impacts, highlighting the need for careful hiring in top positions.
Why Partitioning Is Inevitable
Most jobs in civilian and military fields can be predicted by a person's IQ, with a general accuracy of about 0.4. This means that cognitive ability is a strong sign of job performance. More difficult jobs show an even stronger link to intelligence. A specific case is from New York City in 1939, where almost 30,000 men took tests to join the police force. They were chosen based on their scores, especially on the mental part of the test. Those selected ended up doing very well in their careers and achieved high ranks in the police department, with some even becoming leaders in the field.
Using tests to hire workers can be a smart financial decision for companies. Even tests that are not very strong predictors can still help if only a few applicants are hired or if workers' productivity varies a lot. Even if there are rules against using intelligence tests, knowing about a candidate's intelligence is still important. Employers naturally look for the smartest candidates to build a better workforce, and this focus on intelligence affects how much workers are paid.