data problems

I use a ResMed S9 AutoSet and find differences in the data on previous night events (AHI, OA, etc) between the reading on the S9 panel and what ResScan shows when I read the SSD card on my PC.
What could be the causes for such differences?
Many thanks, any help will be appreciated.

First, Welcome to the Forum!

You have the following report settings available on the S9. They are: 1 Day, 1 Week, 1 Month, 3 Months, 6 Months, and 1 Year. What setting are you using?

Even if you find that S9 results for one day are the same on the machine’s screen and in ResScan 5.1 it wouldn’t mean that it is so for longer periods.

On the screen of my S9 Autoset machine I see these periods and values under SLEEP REPORT:

For periods: 1 day; 1 week; 1 month; 3 months; 6 months; and 1 year.
Also: Days used (in above periods); and Used Hrs.
For values: Pressure; Leak; AHI; Total AI; and Central AI.

That’s it.

ResScan 5.1 Statistics has 12 periods and 4 sleep quality values (the three as above plus Hypopnia Index).

When I check results for 30 days (1 month on the machine’s screen compared to 30 days in ResScan 5.1), by using an SD Memory card and my laptop, I then see close agreement of sleep quality values. I would trust more the values on the machine's screen over those in programs such as SleepyHead, for example, where the program author did the extra statistical interpretation.