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Usage discrepancy - Resmed vs OSCAR
#1
Usage discrepancy - Resmed vs OSCAR
I use a Resmed Airsense 10. On many occasions I have used it for just over 4 hours, according to the machine, which has counted it as a "compliant" day. However, when OSCAR calculates the time from the SD card, it comes up with a slightly lower figure, sometimes dropping below the 4 hour threshold. This creates a red line on the overview chart for a day which the machine decided was ok.  It's only a few minutes but it's not consistent - so maybe it's different rounding errors.

Anyone know anything about this?

I'm still fairly new here. Can someone point me to where I can ask the OSCAR development team about it too? Thanks.
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#2
RE: Usage discrepancy - Resmed vs OSCAR
Posting here is the best way to reach the development team, and you have.

A few minutes difference is typically caused by rounding error in the machine. For each session (mask on to mask off), ResMed rounds the duration to minutes. If there are multiple sessions in the night, it then adds those rounded durations together to obtain the total duration.

OSCAR uses the detailed data written to the SD card by the machine, including session duration in milliseconds. It computes internally using milliseconds and rounds to the nearest second for display purposes.

This difference in duration calculation results in slight differences in AHI and other index calculations. Because the machine is rounding session duration to the nearest minute, OSCAR's numbers can sometimes be lower and sometimes higher than the machine reports.
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#3
RE: Usage discrepancy - Resmed vs OSCAR
(12-22-2021, 08:23 AM)GuyScharf Wrote: ... Because the machine is rounding session duration to the nearest minute, OSCAR's numbers can sometimes be lower and sometimes higher than the machine reports.

Thanks. Sorry I haven't got back earlier.

Yes, that's what I thought, though I've never seen OSCAR reporting higher numbers, it always seems keen on creating a red line if it can. Maybe I wouldn't notice the other cases.

However OSCAR is supposed to follow the ResMed behaviour and it doesn't follow the machine in this respect; I don't know how the official ResMed software behaves.

I feel it would be nice if OSCAR offered the option to round up the session times to simulate the machine. After all, another annoying limitation built into the machine is that a day can only run from noon to noon, yet OSCAR faithfully reproduces it. Compliance is a silly idea at the best of times (one hat fits all), but if the machine says you're OK, I don't think OSCAR should disagree.

Oh well, I'll just set the compliance threshold to zero so I don't have to see ANY red lines. Fortunately, I don't have anyone breathing down my neck about this. Not any more - a technician who told me they wanted to see 100% usage was sent away for re-education in Siberia when I complained. Actually, his boss just said "re-training" but as I haven't seen him since then, I have my suspicions. Mwah-ha-ha-ha! 

Cheers, and Happy New Year!
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