Sunday, July 31, 2011

On the road again..blogging lite..or not at all

Leave for APA in DC on Tuesday and return Sunday. Will be blogging lite or not at all. I shall return



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Saturday, July 30, 2011

Check out the app for APA 2011 Convention

I'm using the mobile app for APA 2011 Convention and think you'd like it too. Here is a link:
http://m.core-apps.com/apa2011

Kevin McGrew


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Kevin McGrew, PhD
Educational Psychologist

The Flynn Effect in MR/ID Capital Cases: To adjust or not to adjust?--That is the question---select PPT slides

I am in the process of finalizing a PPT presentation for an Atkins related invited symposium at APA conference next week. The title of my presentation is in the slide below. (double lick on images to enlarge)





This slide is followed by a few of the introductory slides that related to the first working paper previously posted as part of the Flynn Effect series. Eventually the entire PPT show will be uploaded for on-line viewing. Stay tuned.




















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Monday, July 25, 2011

Sunday, July 24, 2011

FYiPOST: Top-Ten Recent SSRN Downloads

in criminal law and procedure ejournals are here. The usual disclaimers apply. Rank Downloads Paper Title 1 2730 Less than Picture Perfect: The Legal Relationship between Photographers' Rights and Law Enforcement Morgan Leigh Manning, University of Tennessee, Knoxville, College of...





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Kevin McGrew, PhD
Educational Psychologist

Thursday, July 21, 2011

FYiPOST:"Who’s Better at Defending Criminals? Does Type of Defense Attorney Matter in Terms of Producing Fav

The title of this post is the title of this notable empirical paper by Thomas Cohen from the U.S. Bureau of Justice Statistics, which is available now via SSRN. Here is the abstract:

The role of defense counsel in criminal cases constitutes a topic of substantial importance for judges, prosecutors, defense attorneys, scholars, and policymakers.  What types of defense counsel (e.g., public defenders, privately retained attorneys, or assigned counsel) represent defendants in criminal cases and how do these defense counsel types perform in terms of securing favorable outcomes for their clients?

<snip>

Click on link for complete post






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Educational Psychologist

Tuesday, July 19, 2011

More on the problems with the 1 SD (SS =15) / 1.5 SD (22/23 SS) IQ subtest difference rule-of-thumb

In a prior post I raised concerns about the use of the 1 SD (15 SS/3 ss) rule-of-thumb for evaluating differences between two IQ subtest scores that are part of the same composite or cluster. My central point was that this simplistic rule-of-thumb fails to incorporate information regarding the cohesiveness or inter-correlation of the tests within a cluster. More importantly, some human ability domains are more cohesive/tight (e.g., Gc) than others (Gv), and the resulting correlation between two compared tests require the use of the SD (diff) formula that incorporates the correlation between the tests within a domain that are to be compared.

I presented estimated SD (diff) values for select subtest comparisons within the WISC-IV and WJ III in different construct domains. The estimates used the SD (diff) formula that includes the correlation between the measures to be compared.

Knowing that some folks don't like formula's and estimates, I decided to make the point more concrete with real data. A picture is worth a thousand words (or equations).

In the prior post I reported an estimated SD (diff) for the comparison of the WJ III Verbal Comprehension and General Information Gc tests of 9.9, based on their average correlation (across all norm subjects) of .78.

Today I went to the WJ III NU norm data and subtracted all General Information SS's from Verbal Information SS. I then calculated summary stats and generated the histogram below. [Click on image to enlarge]



Beautiful...don't you think? A normal distribution centered on zero (Mean = -0.5) and with an actual data-based SD of 9.8 (9.8 is almost identical to the 9.9 value resulting from the equation method).

Study the graph. It clearly shows that if clinicians want to determine if the WJ III Verbal Comprehension and General Information SS's are 1 SD different (1 SD[diff], technically), then a difference of approximately 10 points is what an examiner should look for...not 15! If an examiner uses the inaccurate rule-of-thumb (i.e, difference of 15 points is 1 SD), in reality the examiner, in the case of these two WJ III Gc tests, is actually requiring a difference of -1.5 SD (diff)....or 15 points.

See prior post for lengthier discussion of the logic, equations, and danger in invoking a subtest difference rule-of-thumb of -1 SD=15 (or, -1 SD = 3 for scaled scores).



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Atkins MR/ID death penalty court decisions: Connor v Hall (Ga, 2011) and Umana v USA (2010)

Doing some file housekeeping. Two miscellaneous Atkins decisions posted to ICDP blogroll today without comment.

Connor v Hall (Ga, 2011)

Umana v USA (2010)


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Friday, July 15, 2011

Humor break: Correlation does not prove causality

Click on image to enlarge. Another great comic from xkcd.


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Intelligent IQ testing: Joel Schneider on proper interpretation of composite/cluster scores







Dr. Joel Schneider has (again) posted an amazing and elegant video tutorial to help individuals who engage in intelligence test interpretation understand whether composite/cluster scores should be interpreted as valid when the individual subtests comprising the composite are significantly different or discrepant (according to Dr. Schneider--"short answer: not very often"). It is simply AWESOME...and makes me envious that I don't have the time or skills to develop similar media content.

His prior and related video can be found here.

Clearly the message is that the interpretation of test scores is not simple and is clearly a mixture of art and science. As Tim Keith once said in a journal article title (1997)...."Intelligence is important, intelligence is complex." This should be modified to read "intelligence is important, intelligence is complex, and intelligent intelligence test interpretation is also complex."


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Sunday, July 10, 2011

FYiPOST: Top-Ten Recent SSRN Downloads

in criminal law and procedure ejournals are here. The usual disclaimers apply. Rank Downloads Paper Title 1 2530 Less than Picture Perfect: The Legal Relationship between Photographers' Rights and Law Enforcement Morgan Leigh Manning, University of Tennessee, Knoxville - College...





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Kevin McGrew, PhD
Educational Psychologist

Sunday, July 3, 2011

FYiPOST: Top-Ten Recent SSRN Downloads

in criminal law and procedure ejournals are here. The usual disclaimers apply. Rank Downloads Paper Title 1 2354 Less than Picture Perfect: The Legal Relationship between Photographers' Rights and Law Enforcement Morgan Leigh Manning, University of Tennessee, Knoxville - College...





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Kevin McGrew, PhD
Educational Psychologist