Dear all:

I was thinking about the creamatocrit discussions and research that is based on conflicts 
of interest and it dawned on me how easy it is to stagger results if people are not aware 
of proper research techniques.

I wish I had the details of the talk I went to at hand to illustrate why the creamatocrit 
would be a lousy diagnostic tool.  As I remember from the talk, the variability from feed 
to feed, breast to breast, minute to minute within the same woman was astoundingly 
large!  If one looks at test weighing, I was surprised that it backs up what all of us know 
from observing infants feed.  Infants usually take a bit more in the morning, but the 
variability feed to feed in total intake is far less than changes in the fat content.  

So, it dawned on me one could simply cheat and stagger the results by having the mother 
pump herself almost dry with masssage, turning the machine on and off, using better 
fitting flanges and then do the creamocrit.  Of course this would not be ethical and it 
would not help educate other health care practitioners about how the fat content changes 
throughout a feeding, nor the body of research cited by Cathy Genna that supports 
volume being more important than measurements of fat content.  

Similarly, the easiest study in the world to design is one that shows no results.  All you 
have to do is simply use a smaller sample size or do sloppy measurements.  The first will 
reduce your statistical power.  The second will increase your variance.   

No test of any kind, no matter how sophisticated is 100% accurate, nor 100% precise.  
All tests have wiggle room or variance.  Some have more variance than others.  The 
more variance, the greater the number of measurements you have to take to 
compensate.  The more measurements you have to take, the more intrusive the test.

As Rachel pointed out, the most important issue is how you are going to use the 
information from the test to make decisions or to educate parents about how to observe 
their infants cues and trust their own observations.  In rare cases, you must really look at 
everything that is going on and one lone diagnostic tool is not really going to give you the 
answer without astute listening and observing and putting together a comprehensive 
picture.  

Best, Susan.

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