Our "stats", according to UC Roll Call (stillbirth/mortality rates mentioned) - Page 2 - Mothering Forums

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Old 02-26-2008, 01:20 AM
 
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I assume though that any deaths that occurred after transfer in the CNM study did not count toward the homebirth stats? As sunnymw said, one of the deaths on the UC roll call occurred in the hospital and was not attributed to the labor being largely unassisted. Maybe that ought to be made more clear on the roll call, because it seems nearly everyone makes the mistake.
To be nit-picky, it was a study of CPMs, not CNMs. Also, all deaths were counted as home birth statistics, regardless of where the death actually occurred. So if the woman's labor started at home, they transferred to the hospital, and the baby died 4 hours after transfer, it would be counted as a home birth. Studies like this always look at intended place of birth, not actual. Otherwise every study of home birth would have a 0% c-section rate! LOL
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Old 02-26-2008, 01:31 AM
 
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Originally Posted by Landover View Post
I just lurk here and on MDC in general, but one of the only things I know about in life is statistics. In getting my PhD I took just about every stat class possible including coursework in quantitative design. An n of 400 is a great sample, and to get a statistically signigicant result with most runs you only need about 30 in your sample.
whether a sample size is good or not depends on how big the effect you want to measure is, and what the noise is.

for example, the data on vaginal breech mortality is not good, despite a huge sample size, because the effect they're looking for (death rate) is tiny, plus the noise is also high (babies with lethal congenital abnormalities being breech because they can't turn). I don't know enough about birth stats to say whether the sample size from the UC population is big enough or not. maybe you could do a power calculation to see?
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Old 02-26-2008, 04:36 AM
 
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Originally Posted by rixafreeze View Post
Studies like this always look at intended place of birth, not actual. Otherwise every study of home birth would have a 0% c-section rate! LOL
... Which also means that the accidental UCs should not be included.

Also, to reduce reporting bias, the births prior to the advent of the roll call sticky (2001? not sure...) should not be included. People are much more likely to say "I had a successful UC in 1973" than they are to say "I intended to have a UC in 1973, but ended up transferring." However, those who were added to the sticky during their pregnancies are recorded regardless of whether they transferred or not, which makes for much more accurate representation of outcomes when UC is intended.
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Old 02-26-2008, 05:32 PM
 
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Originally Posted by Landover View Post
An n of 400 is a great sample, and to get a statistically signigicant result with most runs you only need about 30 in your sample. Statistical signnificance is based on where alpha levels, etc are set - not the amount in your sample. The idea of significance is not applicable here since all she did was look at percentages. I understand that the term was probably just being used in a practical manner, but there is no "significance" in those data either way.

Just wanted you to know that you actually have a pretty good sample here. Yep, there are some confounding variables with self report (as mentioned earlier), but sample size is not an issue. Rixa could probably run some real stats on those data.
Yes, the idea of significance is not applicable when all you do is look at percentages. But I'm not following you with the rest of it. The alpha level is useful when we can't know absolute percentages, but it's not an objective value. If a sample size of 30 was just as meaningful as that of 5000, why bother with the larger number?

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Originally Posted by rixafreeze
So if the woman's labor started at home, they transferred to the hospital, and the baby died 4 hours after transfer, it would be counted as a home birth. Studies like this always look at intended place of birth, not actual. Otherwise every study of home birth would have a 0% c-section rate!
That makes sense for c-section stats, but it's misleading as far as death rate. I'm surprised that they don't take it further and differentiate between death-at-home and death-in-hospital.

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Originally Posted by kaylee18
Also, to reduce reporting bias, the births prior to the advent of the roll call sticky (2001? not sure...) should not be included. People are much more likely to say "I had a successful UC in 1973" than they are to say "I intended to have a UC in 1973, but ended up transferring." However, those who were added to the sticky during their pregnancies are recorded regardless of whether they transferred or not, which makes for much more accurate representation of outcomes when UC is intended.
Yes -- if we're looking at death rate, we should only count from that point (which I think would be a group of more like 300.)
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