Larry v Branker (NC, 2009). More voodoo psychometrics via SEM misuse/abuse and use of SSSQ

Another addition to the Atkins Court Decisions section of the ICDP blog. And, unfortunately, another case the reflects the courts failure to recognize professionally accepted psychometric standards (viz., failure to consider standard error of measurement--SEM; and the use of adaptive behavior instruments that are inappropriate for norm-referenced "relative standing" in a population comparisons).  Another case of voodoo psychometrics.


Thanks to Kevin Foley for sending the Larry v Branker (NC, 2009) decision.

Upon review, this appears to be yet another case where a bright line IQ score of 70 is used to render a Dx of MR.  That is....70 or below...DX=MR....71 to 75 = not MR.  The defendant obtained a Full Scale IQ score on the WAIS-III of 74, which is within the professionally accepted range for a Dx of MR (when taking into account "measurement error".)  Not taking into account the standard error of measurement (SEM) is at odds with the two major professional associations (AAMR/AAIDD; American Psychiatric Association DSM) that are always mentioned as providing the operational definition of MR in Atkins decisions.  APA and AAIDD (as well as all major measurement associations) make it extremely clear that SEM must be part of "best practices" when diagnosing MR.  The use of SEM is interpreted by professional associations, psychometric experts, and most psychological testing experts, as recognizing scores as high as 75 (70 plus or minus 5 IQ pts) in a possible Dx of MR. 

The continued failure of certain courts, judges, states, and some psychologist "experts" to recognize the well-established measurement concept of "measurement error" (as reflected by the SEM statistic) is troubling....very disturbing.  I will eventually be making a post re: the concept of SEM...in hopes of educating folks on the logic, statistics, and support for recognizing measurement error in MR Dx....esp. in Atkins cases.  The recent law review article by Blume is an excellent read regarding the failure of many courts to recognize the accepted practice of bracketing IQ scores with the SEM---and often in a manner that appears to be a deliberate attempt to circumvent the intention of the U.S. Supreme Courts original landmark Atkins v Virginia decision.  Some courts and judges continue to play foot-loose and fancy-free with psychometric concepts that they clearly fail to understand or, simply deliberately interpret inappropriately to justify a predetermined biased decision.  People with MR are continuing to be executed due to SEM misuse and abuse.   It appears the Larry Court hid behind statutory language: "The statute defines '[significantly subaverage general intellectual functioning' as '[a]n intelligence quotient of 70 or below.' Id" rather than employing reflective critical thinking in accordance with accepted professional standards. 

Also, as has been seen in other decisions,the SSSQ was inappropriately accepted as a measure of adaptive behavior.  Another example of voodoo psychometrics (click here for my prior comments on the use of the inappropriate use of the SSSQ in the formal Dx of MR. ) The SSSQ may be an appropriate instrument for which it was developed and/or normed, but is not an appropriate nationally normed measure of AB...which is required as per the Joint Test Standards when making inferences regarding a persons relative standing within the population.

Technorati Tags: psychology, forensic psychology, school psychology, educational psychology, neuropsychology, IQ, intelligence, IQ tests, IQ scores, standard error of measurement, SEM, MR, ID, mental retardation, intellectual disability, SSSQ, adaptive behavior, Atkins cases, Atkins hearings, death penalty, Atkiins v Virginia, capital punishment, Larry v Branker, voodoo psychometrics

Woods v Texas (2009): Another Atkins MR death penalty decision psychometric quagmire

Woods v Texas (2009) is the most recent (October 7, 2009) Atkins mental retardation death penalty decision I've come across (now added to Court Decisions listings).  Woods denial of classification of mental retardation was previously decided in 2008 (Woods v Texas, 2008).  And, per usual with these decisions, the decision contains a quagmire of psychometric issues.  Although I've stated previously that I'm no longer shocked at some of the psychometric testimony and the courts interpretations and decisions (sometimes which border of voodoo psychometric logic), I guess I still am....but more a form of numbness to some of the material I have read.  Woods v Texas (2009) does not disappoint with a boat-load of psychometric issues that need further exploration.

As I've stated previously, I simply can not keep up with these cases.  Each requires considerable study and reflective thought...and I currently lack the time to do each justice.  Rather than sit on these decisions until I have the time, I'm posting them so others, who may have the time or motivation, may dissect them and possibly offer comments via the comments feature of this blog or, and my preference, to submit a guest blog post for publication at this site.

The above being said, I've done a very quick skim of the decision and see some of the "old familiar" measurement issues being present, and some "newbies".  Below is a sampling of issues that need to be addressed in sfuture post:

• Flynn Effect
• Standard error of measurement (SEM)
• Diagnosis of MR before the age of 18.  Especially in the presence of IQ testing during the school years that produced IQ scores of 78 and 81, yet Wood's was diagnosed as learning disabled (LD) and not MR.  I've yet to delve into the whole issue of the accuracy of school-based classifications.  Having been a school psychologist for 10+ years, during the time when IQ tests where under serious fire for MR classification, esp. for minority students (the famous  Larry P. decision that sent shock waves through the psyche of many school psychologists when it came to classifying any minority student as MR even when faced with IQ test scores that were in that range), I know that many students were given the more politically easy Dx of LD to avoid the potential fallout of  labeling someone (esp. a minority student) MR.  It was simply the "easy way out"....yet now I wonder if these decisions are clouding Atkins rulings related to the third prong of the definition of MR (Dx prior to age 18).  This is another whole post or series of posts.
• Adaptive behavior (AB) definition.   I see in the decision, that in the same breath, both adaptive behavior and maladative behavior, which are separate constructs, are discussed as they exist under the single umbrella of adaptive behavior.  This relates to the discussion of the Scales of Independent Behavior--R (SIB-R) adaptive and maladaptive index scores.  Yet another long post or series of posts.  Toss in Texas' unique Briseno twist on adaptive behavior and there is much to dissect.
• Adaptive behavior (AB) assessment.  Aside from using an appropriate nationally normed measure of AB (SIB-R), I'm dumbfounded by the use of the SSSQ as a measure of AB, given that the SSSQ was normed on a sample of individuals with disabilities.  Woods apparently scored 95, which was in the normal functioning range when compared to other individuals with disabilities.  This would be analagous to developing WAIS-III/IV IQ norms based only on a sample of individuals with mental retardation, and then giving the test to a person and saying they are average or normal.  It would only tell you that when compared to other individuals with MR, they are better functioning than most so classified people.  Standardized psychometric instruments (IQ or AB) used in Atkins decisions  should only be based on nationally representative samples characteristic of the populatlion of the US....not a select subsample of individuals with disabilities.  This makes no sense. 
  
• Competency to stand trial.  Then there is the use of an instrument I've not yet familarized myself with..the Competency Assessment to Stand Trial For Defendants with Mental Retardation (CAST-MR).  This may be an excellent psychometric tool....I need to examine it and determine how it fits in the whole Atkins three-prong defintion of MR for death penalty cases.  It has been my understanding (which I need to verify) that competency to stand trial is a separate issue from determination of mental retardation.  Again....I suspend judgment and comments until I can get up to speed on this instrument.  That being said, a skim of the decision suggests the scores were used when debating whether Woods was MR...hmmmm.....doesn't seem appropriate.
  
• Short form IQ tests.  Do short form screening IQ tests (e.g., WASI) have any place in Atkins MR determination?

More than enough to chew on. 

Technorati Tags: psychology, forensic psychology, criminal psycholoyg, criminal justice, Atkins case, MR, mental retardation, intellectual disability, developmental disability, IQ, IQ tests, IQ scores, adaptive behavior, Briseno, SSSQ, CAST-MR, Larry P decision, Woods v Texas, capital punishment, death penalty, SEM, standard error of measurement, psychometrics, voodoo psychometrics, special education classifications, WAIS, Wechsler IQ tests