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      in Statistics

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 4.  High School & College
     Statistic Teachers


1. Harvard led MI study

2. JACC study 

   (J. of Amer. Coll.

3. NEJM cath study

4. Amer. J. of Cardio.
    review of literature


Oat bran study

Pregnancy & Alcohol

Are Geminis really
9. Columbia 'Miracle' Study  

Additional Topics:


Limitations of Meta-Analyses

Large Randomized Clinical Trials

Tale of Two Large

Advocate meta-analyses

Network meta-analyses




A statistical analysis in a major medical journal (Journal of American College of Cardiology- JACC) which was so bad, that it may have led to a subsequent improvement

The study in which this statistical problem occurred:

In the Journal of American Cardiology (JACC), which is the official journal for the society of board certified cardiologists, there was an article with a major statistical error. This involved a study with the title of “Increased Myocardial Perfusion at Rest and Diminished Perfusion Reserve in Patients With Angiographic Normal Coronary Arteries” (Geltman EM, et al. JACC 1990; 16:586-95). The article illustrates a fundamental flaw in the use of statistics.

An Analogy regarding
this statistical problem

A way to make this fundamental statistical error more understandable is to note the following analogy.  A study examines two groups of people, one group from north of town (northerners) and one group south of town (southerners). The northerners were then divided into the tall northerners and the short northerners on the basis of height. The researchers then inappropriately compared the tall northerner group to the entire undivided southerner group. 

Naturally, the tall northern subgroup who were selected on the basis of being tall would on the average be taller than the undivided total southern group. Similarly, the tall northerner group would also be likely to have a statistically greater value for a foot to waist measurement than the average value for the undivided southerner group. However, one could not say that because of this comparison, that there is a unique subgroup that exists in the northerners of tall people that doesn’t exist in the southerner group. This is fundamental error that the authors of this study made. It was perhaps less obvious because the measurements they used involved PET scanners and cardiac measurements, but that doesn’t make this inappropriate statistical analysis any less wrong than it is for the example given of people divided on the basis of height.

Some types of statistical analysis are inherently invalid:

Analogy explaining the statistical problem in the JACC (Journal of American Cardiology) article  (click here) 

Details of statistical problem in JACC article (click here)

See right column for analogy of this statistical problem.

A letter advocating an improvement in the Journal's review process was sent to each of the editors:
This letter was
sent to each individual JACC editor calling for a formal statistical review of each article prior to publication to avoid comparable major statistical errors. (click here)  

 See comments by one of JACC editors (click here)  Reply from one of the JACC editors agreeing that this problem deserved further consideration. 

An improvement was later made in the journal's review process:

Announcement by JACC editors that every manuscript that is strongly considered for publication will be first reviewed for statistical issues.  (click here)

Further analysis:

Complete analysis of statistical problem sent to the editors of JACC  (click here)

Whether influenced by this correspondence or not, ultimately, a change was made by JACC and a statistical review was incorporated into their review process.






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