(10-09-2015, 07:19 PM)eseedhouse Wrote: ...This may be true, but a ton poor data is outweighed by a single night of good data. A properly done overnight sleep study is definitive...
Your first statement here may also be true (the second is not). But who is to say whether PSG data is that much better? According to the quotes from researchers who have studied this in earlier posts right here in this thread the big secret is that (Pssst! It's not!)
You also qualified this with "properly done". To me that implies an environment that is conducive rather than upsetting, and a full night's sleep as the basic sample. My study had neither of those, and if you read the posts, most who post here have anecdotally about the same experience.
Even if "properly done", a PSG is NOT definitive, for two reasons I stated earlier:
1. Events are never defined; they are on a sliding scale as to their duration, severity, and even whether they are one type of event or another. There is no black and white, until the events are counted up. Something has to be just over a particular threshold before it is even recognized. There is nothing exactly defined, and both the PSG and the APAP try to pigeonhole what they flag into defined categories for the purpose of simply counting them in those categories, as defined events, which they are not. That is like taking the Mona Lisa and digitizing it at a low, blocky sample rate and depth, and so there is a lot of guesswork where grey is supposedly either black or white, which it isn't. Its grey.
2. No measurement in either the PSG or the APAP back-pressure measurement is direct. No events are measured directly, because there is no way to do that. A belt around your chest that measures how much you expand your chest during a breath does not measure how you breathe, it measures how much you expand your chest, which is indirect, and the determination has to be interpolated from that indirect data. They are educated guesses based on secondary or tertiary data not even directly related to those events. That dithers the accuracy, eliminating the possibility of being "definitive".
And a PSG is a snapshot. One set of data points. A single sample set. The APAP gets a whole new set of data points every night, as conditions change.