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Understanding the 95th Percentile/Median etc?
#1

Greetings fellow Hoseheads,

On Night 23 here. Working to get under 5.0 AHI consistently. Have had maybe 10 nights under 5.0 out, 4 of them in the last week, so trending is improved hopefully.

When I look at my data both simple and complete, I note that the simple breaks the overall numbers into median, 95th percentile and maximum (not necessarily in that order)

My understanding is that the 95th percentile is where you are spending the MOST of your time at. Is that correct? Is that the number wants to focus as the most?

Also what do I make of median? I thought that was the middle number between max and least but it can't be because except one day, my median says 0.0.

I get Mr. SmileyGrin
on my machine every day. But I figure, still lowering leaks may help my AHI?

Thanks in Advance.

Susan BabyHoseHead in S.F.
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#2
median - if you have 300 readings, arranged in numerical order, the median is the 150th number. If you had 0 reading for 60% of the time, 0 is the median.
95th percentile is - 95 percent of the numbers are at or UNDER the 95th percentile number.
Smile

for the following group of numbers:
0 0 0 0 12 80 95
median = 0
mean (average) = 31.17
86th percentile = 80 (6 out of 7 values are at or under 80)


if I spent 80% of my night at lowest pressure setting (say 6 cmH2O), and I have 20% nasty stuff where the machine combats them up to 12 cmH2O; and I find out that my 95% percentile pressure is 10.5 cmH2O and say my AHI for the night was 7.23, OA of 3.5, CA of 0.9 and H of 2.83 ...

then, to figure out a better setting:
1. I might know an upward adjustment is ok to try since CA are still low.
2. adjusting to 12 don't make sense.
3. adjusting to 10.5 would theoretically take care of most of the apneas. unfortunately you may cause more CAs in the process.
4. so you pick something between 6 and 10.5. if you are a talented guesser or had some advice from others you might seize upon a good number.
5. say in this case your median was 7.6. think it might make sense to raise it to at least 7.5 cmH2O?

That is kind of in a nutshell why we are here trying to help...
Smile
Dedicated to QALity sleep.
You'll note I am listed as an Advisory Member. I am honored to be listed as such. See the fine print - Advisory Members as a group provide advice and suggestions to Apnea Board administrators and staff concerning Apnea Board operation and administrative policies. Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
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#3
95th percentile number means leak or pressure was at or below this number for 95% of the night

Median number means leak or pressure was at or below this number for 50% of the night

My A10 setting: Autoset 10-13, EPR & Ramp off
Last night data
Hours: 7.30 - 1 mask event
AHI: 0.1 - % of time in CSR
Pressure: Med 10.9 - 95th 11.9 - Max 12.6
Leak: Med 0.0 - 95th 2.4 - Max 16.8

Sleep-well





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#4
(01-19-2015, 01:36 AM)zonk Wrote: 95th percentile number means leak or pressure was at or below this number for 95% of the night

Median number means leak or pressure was at or below this number for 50% of the night

My A10 setting: Autoset 10-13, EPR & Ramp off
Last night data
Hours: 7.30 - 1 mask event
AHI: 0.1 - % of time in CSR
Pressure: Med 10.9 - 95th 11.9 - Max 12.6
Leak: Med 0.0 - 95th 2.4 - Max 16.8

Sleep-well


WOW Zonk, I can only dream of a 7.5 hour mask event! Lovely.


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#5
you might read RobySue's blog on CPAP statistics:
http://adventures-in-hosehead-land.blogs...de-to.html
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#6
I hadn't but I did at your suggestion. Thanks Mongo.

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