offset time

[sedge]

I hadn't thought of two numbers the same LOL

But then of course your Standard Deviation will be mahoosive cos your BG is hardly never gonna be 5.5 when you test it!

[everydayupsanddowns]

Yes Winni but it doesn't aim for 4 or 8, it tells you the exact correction I would give anyway, without the pump, to bring me to 6 or whatever the midpoint was.  It has to be between 2 numbers so I spose you'd have to tell it 5.4 to 5.6.

But are you saying if you tested and you were 4.5, you'd have  some CHO to get yourself up to 5.5 ?  or really truly honestly correct if you were at 6.5? 

Or are you saying that's what you want to be 24/7 on your basal tests?

The micro-corrections are part of the benefit for me. Not that I'd give one at those levels on its own, but when a meal bolus is calculated I'd like the pump/Expert to add (or subtract!) a sliver of a unit here and there to improve the dose and, hopefully, get me to mid-range next mealtime.

Incidentally Sedge that's not my understanding of how SD works. I don't think the set range matters (I get SD in spreadsheets that don't know the range at all). The SD is just how spread or bunched a collection of results are around the mean. So average BG 6 with SD 2 means almost all results would come between 4 and 8 (SD is in the same units as the readings). At least I think that's how it works!

[nytquill17]

SD is the average distance of each data point from the average of the entire group.  Like if you give me a bunch of readings, I could add them all up and divide by the total number to tell you what the average is.  But that doesn't tell you whether you have many outlying readings on either side or if they are all bunched up together (the same problem as with having an A1c done with no daily readings to compare to).

If your average of all the readings is, say, 6.  And you look at one reading of 9, that reading is 3 points away from the measured average.  If you also have a reading of 3, that reading is 3 points away in the other direction from the midpoint.  So you add 3 and 3, divide by two, you get a standard deviation of 3.

Compare that to if you got an average of 6.6 by having one reading of 5, one reading of 7 and one of 8.  The 5 is 1.6s point away from the group average.  The 7 is 0.4 points away, and the 8 is 1.4 points away.  1.6 + 0.4 + 1.4 =  3.4.  Divide by 3 and you get 1.13 or in other words a much closer spread.

In statistics, at any rate, it's calculated not based on a number that you pick, but on the mathematical average already contained in your data points.  Although I suppose you could calculate the amount of variability in relation to a given number or a goal that you set but that wouldn't be a "true" standard of deviation, I don't think.

[sedge]

Oh right, I thought it was SD from the target !  That's why I didn't understand.  So it doesn't really tell you much LOL of itself - except to know whether all your results are close-ish or further apart ..... I see in the last week, between 05.30 and 11.00 my results are within 1.1.

Virtually all the others over time are above 3.0.  Some of em well above ......

I do really need to get on track again ......

[everydayupsanddowns]

John Walsh (I think?!) comments that ideally in D terms you want to aim for a decent 'in range' average and an SD of no more than a third of that average.

Now that really would be nice!

(please note this is not *yet another* stick to beat ourselves with, but it helps me work out whether what feels like wobblier months really are wobblier...)

[cjo20]

Oh right, I thought it was SD from the target !  That's why I didn't understand.  So it doesn't really tell you much LOL of itself - except to know whether all your results are close-ish or further apart ..... I see in the last week, between 05.30 and 11.00 my results are within 1.1.

Virtually all the others over time are above 3.0.  Some of em well above ......

SD doesn't actually give the range they were spread over directly. If your average BG was 7, with a SD of 1.1 it means that:

68% of your readings would be between 5.9 and 8.1
95% of your readings would be between 4.8 and 9.2
99.7% of your readings would be between 3.7 and 10.3

This is assuming that your readings are spread around the average in a certain way (more tightly grouped around the mean).

1.1 is a pretty good SD imo.

[sedge]

Yes but that's only at that time of day in the last week.  They don't stay the same for 14 days, 30, 60 or 90 !

Though it is comforting that my blood is more in control sometimes when I'm asleep and therefore have no impact on it.......

NOT.

LOL

[vicktrick]

i've set my combo to be 5.5, both numbers.