<p>Correcting for range restriction seeks to estimate the association (typically correlation) between two variables where the range on one or both variables has been reduced. It is typical to distinguish between direct and indirect range restriction. Direct range restriction occurs where the sample as been restricted based on scores on one or both variables. Commonly, this arises in employee and student selection contexts, where for example an intelligence test might be used to determine whether someone gets a job or whether a student is admitted into a program. In particular, the prototypical example occurs where there is a hard cut-off. Indirect range restriction arises where selection occurs based on some other variable that is associated with the variables of interest. This is much more common. For instance, students might be selected on past academic grades which are correlated with intelligence.</p>
<p>You ask the question: is this equivalent to asking &quot;how well would people who don't go to college do in college?&quot;</p>
<p>The answer in rough terms is yes. More specifically, it is seeking to estimate the correlation in some larger population. The definition of this larger population depends on your definition of the target population. In particular, the target population would include students admitted into college and some subset who are not admitted to college (or not the college that you are focussed on).</p>
<p>Implicit in your question is: why would you want to know that?
A common scenario is where you are trying to evaluate the effectiveness of a selection tool. For instance, say you are using an intelligence test to determine admission decisions. But you only have data on intelligence and academic grades for students admitted on the basis of the intelligence. What you really want to know is the correlation between applicant intelligence and academic grades. Because it is that validity that determines the utility of using the intelligence test in selection. Corrections for range restriction give you tools to do this.</p>
<p>Other times, you are honestly interested in the research question in order to understand the world. I.e., what is the relationship between intelligence and academic grades in the whole population.</p>
<p>Of course, there are many complications. In particular, often you would be incorporating proxies for intelligence in your selection process anyway (e.g., using past academic grades, interview performance, etc.). So the actual incremental value of the intelligence test in selection will be more complicated.</p>

CC BY-SA 4.0
2021-10-08T03:02:11.800Z
2021-10-08T03:02:11.800Z
Jeromy Anglim
<p>Specifically, it seems to me that correcting for range restriction of IQ in things like college is like asking &quot;how well would people who don't go to college do in college?&quot;</p>

CC BY-SA 4.0
2021-10-07T14:55:28.973Z
Can you give an example?
Bryan Krause
CC BY-SA 4.0
2021-11-07T06:35:27.400Z
Welcome to Psychology.SE. We work differently to many SE sites, where we have a strict policy that all questions should [show evidence of prior research](https://psychology.meta.stackexchange.com/q/993). Please help us to help you and [edit] your question to provide more information on what you have read about range restriction correction in IQ studies, and any problems you are having understanding your research. If you found nothing, what did you Google? This helps to provide an answer which will be more helpful.
Chris Rogers
<statistics>
what's the point of range restriction correction in IQ studies?
gndz
# what's the point of range restriction correction in IQ studies?

(Asked by: username_0 on 2021-10-07)

Specifically, it seems to me that correcting for range restriction of IQ in things like college is like asking "how well would people who don't go to college do in college?"

**Tags:** statistics

> **Comments:**
> **username_1**: Can you give an example?  
> **username_2**: Welcome to Psychology.SE. We work differently to many SE sites, where we have a strict policy that all questions should [show evidence of prior research](https://psychology.meta.stackexchange.com/q/993). Please help us to help you and [edit] your question to provide more information on what you have read about range restriction correction in IQ studies, and any problems you are having understanding your research. If you found nothing, what did you Google? This helps to provide an answer which will be more helpful.  

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## 1 answers

### Answer by username_3 on 2021-10-08. Score: -1

Correcting for range restriction seeks to estimate the association (typically correlation) between two variables where the range on one or both variables has been reduced. It is typical to distinguish between direct and indirect range restriction. Direct range restriction occurs where the sample as been restricted based on scores on one or both variables. Commonly, this arises in employee and student selection contexts, where for example an intelligence test might be used to determine whether someone gets a job or whether a student is admitted into a program. In particular, the prototypical example occurs where there is a hard cut-off. Indirect range restriction arises where selection occurs based on some other variable that is associated with the variables of interest. This is much more common. For instance, students might be selected on past academic grades which are correlated with intelligence.

You ask the question: is this equivalent to asking "how well would people who don't go to college do in college?"

The answer in rough terms is yes. More specifically, it is seeking to estimate the correlation in some larger population. The definition of this larger population depends on your definition of the target population. In particular, the target population would include students admitted into college and some subset who are not admitted to college (or not the college that you are focussed on).

Implicit in your question is: why would you want to know that?
A common scenario is where you are trying to evaluate the effectiveness of a selection tool. For instance, say you are using an intelligence test to determine admission decisions. But you only have data on intelligence and academic grades for students admitted on the basis of the intelligence. What you really want to know is the correlation between applicant intelligence and academic grades. Because it is that validity that determines the utility of using the intelligence test in selection. Corrections for range restriction give you tools to do this.

Other times, you are honestly interested in the research question in order to understand the world. I.e., what is the relationship between intelligence and academic grades in the whole population.

Of course, there are many complications. In particular, often you would be incorporating proxies for intelligence in your selection process anyway (e.g., using past academic grades, interview performance, etc.). So the actual incremental value of the intelligence test in selection will be more complicated.


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