What exactly does the 95% stat mean?

jules · Post by **jules** » Fri Nov 23, 2007 11:46 am

If we had the 95 %ile marked on a plot of data, then tail to the right would have 5 % not 2 1/2 % of the data values. This is true whether the graph is of a normal distribution or a skewed distribution.

For a normal distribution 95 % of the data corresponds to being about 2 standard deviations from the mean. In this case there is 2.5 % of the data under the tail on each side. In a normal distribution the graph is symmetrical, the mean (average) = median = mode.

I will refer anyone interested in more on normal distributions to http://en.wikipedia.org/wiki/Normal_distribution.

When using all of this data you get off the LED or from the software, please remember to not make changes each night as one night's numbers isn't enough to decide your pressure.

Jim,

That 95% (or in the case of Respironics, 90%) is, statistically speaking, a way to define the characteristics of the curve and the significance. Think of a bell-shaped "normal" curve. 95% significance means the whole area under the curve except 2 1/2% at each of the "tails" of the curve. Thus if your AHI is below 5 and leak rate and shape are good (i.e. you don't have large leaks and leak graph doesn't look like a whole series of mountains and valleys), it would tend to indicate that the "95% pressure" is just fine. If your AHI is above 5 and/or leak rate doesn't look good, you'd probably want to increase the top end of your range.

Mindy

soulrhythm · Post by **soulrhythm** » Fri Nov 23, 2007 12:25 pm

Well...my wife and I usually sleep on the futon in the basement when company comes. We'd rather give our guests the better bed...It's a hospitality thing, I guess.

Again, thanks everyone for the quick replies. They have been very helpful. I tried to find AutoScan software, but couldn't find it anywhere. Google mostly came up with matches from CPAPTalk.

DreamStalker · Post by **DreamStalker** » Fri Nov 23, 2007 12:34 pm

I believe that ResScan has superceded AutoScan for ResMed software ... again, our forum host sells it and the card reader.

mindy · Post by **mindy** » Fri Nov 23, 2007 12:40 pm

jules wrote:If we had the 95 %ile marked on a plot of data, then tail to the right would have 5 % not 2 1/2 % of the data values. This is true whether the graph is of a normal distribution or a skewed distribution.

...

When using all of this data you get off the LED or from the software, please remember to not make changes each night as one night's numbers isn't enough to decide your pressure.

Yes, Jules, thanks for the correction.... hasty typing and fogged brain cells were the culprit!

Mindy